Optical film, and polarizing plate and liquid crystal display device employing same

ABSTRACT

The inventions are an optical film containing cellulose acylate and a compound having a structure denoted by General Formula (A) described below, and a polarizing plate and a liquid crystal display device employing the optical film. 
                         
L represents n-valent connecting group, n represents an integer of greater than or equal to 2, and A represents a heterocyclic group denoted by General Formula (I). R 1 , R 3 , and R 5  represent a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, or a heteroaryl group. Here, any one of R 1 , R 3 , and R 5  is bonded to L.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT International Application No.PCT/JP2014/068356 filed on Jul. 9, 2014, which was published under PCTArticle 21(2) in Japanese, which claims priority under 35 U.S.C. § 119(a) to Japanese Patent Application No. 2013-144547 filed in Japan onJul. 10, 2013. The above applications are hereby expressly incorporatedby reference, in their entirety, into the present application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical film, and a polarizing plateand a liquid crystal display device employing the same.

2. Description of the Related Art

An optical film such as a cellulose acylate film has been used invarious liquid crystal display devices as an optical member of theliquid crystal display device, for example, a support of an opticalcompensation film, a protective film of a polarizing plate, and thelike.

The liquid crystal display device has been used in indoor such as in aTV, and for example, has been increasingly used in outdoor mainly for aportable device. For this reason, a liquid crystal display devicecapable of withstanding hygrothermal conditions has been required to bedeveloped from the related art.

In addition, a demand for the liquid crystal display device to beresistant to severe usage conditions in extensively various purposes hasbeen increased, and annually, durability has been required to be at ahigher level than that of the related art.

In addition, recently, the liquid crystal display device has beenenlarged and thinned mainly for a TV, and according to this, the opticalfilm which is a configuration member is required to be thin. From therelated art, it has been important for the optical film to have suitablehardness and excellent cutting properties from a viewpoint ofworkability, and the thinned optical film is further required to haveimproved hardness and cutting properties.

In the optical film using the cellulose acylate film, it has been knownthat a specific compound is contained in the optical film in order tosolve various problems in further improving performance, in propertiesas the optical film, or in manufacturing.

For example, in order to suppress a variation in retardation of theoptical film due to environment humidity, a barbituric acid compound(refer to JP2011-118135A) has been proposed in which one of a 5-positionis a hydrogen atom and the other is a group having a specific Hammett σmor σp value. In addition, in order to enhance durability of a polarizer,a barbituric acid compound (refer to JP2011-126968A) has been proposedin which one of a 5-position is a hydrogen atom and the other is an arylgroup. Both of these compounds have a hydrogen atom in the 5-position,and are compounds which physically and chemically function as an acid.In order to enhance peelability from the support body in solution filmformation and to enhance durability of the polarizer by furtherdeveloping these compounds, it has been also proposed that a specificorganic acid is contained in the optical film (refer to JP2012-72348A).

SUMMARY OF THE INVENTION

According to the examination of the present inventors, it has been foundthat a new object due to the addition of various additives at the timeof further enhancing the durability of the polarizer under hygrothermalconditions is also required to be attained. The new object, for example,is to suppress coloration of a film due to light. In addition, it hasbeen found that further improvement in the hardness of the optical filmand the durability are required to be compatible.

An object of the present invention is to provide an optical film inwhich optical properties or durability are enhanced, in particular,coloration of a film due to light is suppressed, deterioration of apolarizer at the time of being aged under hygrothermal conditions bybeing bonded to a polarizing plate is suppressed, haze is low, andhardness is high. Further, another object of the present invention is toprovide an optical film which is able to further increase performance ofa liquid crystal display device, and a polarizing plate and a liquidcrystal display device employing the optical film.

In order to attain the objects described above, the present inventorshave examined a relationship between various additives and variousperformances. As a result thereof, it has been found that when abarbituric acid derivative having a specific structure is added to acellulose acylate film, hardness of the film is improved, and thuscoloration due to light irradiation is suppressed by the structure ofthe barbituric acid derivative. For this reason, as a result of furtherexamination, it has been considered that, in a compound having amolecular structure in which barbituric acid skeletons are denselyarranged, the barbituric acid skeletons mutually interact with celluloseacylate molecules, and thus a free volume in the film is able to beeffectively reduced, and film hardness is improved. According to thisconsideration, the molecules are further designed, and a relationshipwith respect to an action for suppressing film coloration due to lightirradiation is examined, and thus the present invention has beenaccomplished.

That is, the object described above is attained by the following means.

<1> An optical film containing cellulose acylate and at least one typeof a compound denoted by General Formula (A) described below.

In General Formula (A), L represents an n-valent connecting group, nrepresents an integer of greater than or equal to 2, and A represents aheterocyclic group denoted by General Formula (I) described above.

In General Formula (I), R¹, R³, and R⁵ each independently represent ahydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, anaryl group, or a heteroaryl group. Here, any one of R¹, R³, and R⁵ isbonded to the L.

<2> The optical film according to <1>, in which L is a single bond, analkylene group, a cycloalkylene group, an alkenylene group, analkynylene group, an arylene group, a heteroarylene group, —O—, —S—,—NR— (R represents a single bond, a hydrogen atom, an alkyl group, acycloalkyl group, an aryl group, or an acyl group), —C(═O)—, —SO—,—SO₂—, an arenetriyl group, a heteroarenetriyl group, or a connectinggroup formed by combining thereof.

<3> The optical film according to <1> or <2>, in which the total numberof ring structures in L, R¹, R³, and R⁵ is 1 to 6.

<4> The optical film according to any one of <1> to <3>, in which n is2.

<5> The optical film according to any one of <1> to <4>, in which thecompound denoted by General Formula (A) is denoted by General Formula(A-1) or (A-2) described below.

In General Formulas (A-1) and (A-2), R¹¹, R¹², R³¹, R³², R⁵¹, and R⁵²each independently represent a hydrogen atom, an alkyl group, acycloalkyl group, an alkenyl group, an aryl group, or a heteroarylgroup, and X represents a single bond or a bivalent connecting group.

<6> The optical film according to <5>, in which X has a methylene group,and a carbon atom in the methylene group is bonded to a barbituric acidskeleton.

<7> The optical film according to any one of <1> to <6>, in which in thecompound denoted by General Formula (A) described above, the numberof >NH partial structures in molecules is less than or equal to 3.

<8> The optical film according to any one of <1> to <7>, in which atotal degree of acyl substitution A of the cellulose acylate satisfiesthe following expression.1.5≤A≤3.0

<9> The optical film according to any one of <1> to <8>, in which anacyl group of the cellulose acylate is an acetyl group, and a totaldegree of acetyl substitution B satisfies the following expression.2.0≤B≤3.0

<10> The optical film according to <9>, in which the total degree ofacetyl substitution B is greater than or equal to 2.5 and less than2.97.

<11> The optical film according to any one of <1> to <10>, in which theoptical film contains at least one type of a plasticizer.

<12> The optical film according to any one of <1> to <11>, in which theoptical film is formed of at least two layers including a layercontaining the cellulose acylate and at least one type of the compounddenoted by General Formula (A) described above and a hard coat layer.

<13> A polarizing plate including a polarizer; and the optical filmaccording to any one of <1> to <12> on at least one surface of thepolarizer.

<14> A liquid crystal display device, at least including the polarizingplate according to <13>; and a liquid crystal cell.

Herein, a numerical range denoted by using “to” indicates a rangeincluding numerical values described before and after “to” as a lowerlimit value and an upper limit value.

In addition, herein, a “group” described as each of the groups, unlessotherwise stated, is used for indicating either a non-substitutionalgroup or a group having a substituent group. For example, an “alkylgroup” indicates an alkyl group which may have a substituent group. Inaddition, herein, an “aliphatic group” may be a straight-chain aliphaticgroup, a branched aliphatic group, or a cyclic aliphatic group, or maybe a saturated aliphatic group or an unsaturated aliphatic group (whichdoes not become an aromatic ring).

Herein, when a plurality of substituent groups or connecting groups(hereinafter, referred to as a substituent group and the like) areconcurrently or selectively defined, the respective substituent groupsand the like may be identical to each other or different from eachother.

According to the present invention, it is possible to provide an opticalfilm in which optical properties or durability are enhanced, inparticular, coloration of a film due to light is suppressed,deterioration of a polarizer at the time of being aged underhygrothermal conditions by being bonded to a polarizing plate issuppressed, haze is low, and hardness is high. Further, it is possibleto provide an optical film which is able to further increase performanceof a liquid crystal display device, and a polarizing plate and a liquidcrystal display device employing the optical film.

The above-described and other characteristics, and advantages of thepresent invention will be obvious from the following description withsuitable reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example schematically illustrating an inner structure of aliquid crystal display device of the present invention.

FIG. 2 is an example schematically illustrating an inner structure ofanother liquid crystal display device of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the present invention will be described in detail withreference to embodiments.

[Optical Film]

An optical film of the present invention is formed of at least one layerof a cellulose acylate film containing cellulose acylate and at leastone type of a compound denoted by General Formula (A). In addition, theoptical film may be configured of a plurality of layers, and thecompound denoted by General Formula (A) may be contained in any one orany plurality of the layers or in all layers.

Here, a cellulose acylate film or a cellulose acylate layer indicatesthat cellulose acylate is contained in a resin component configuring thefilm or the layer in the amount of greater than or equal to 50 mass %.Here, the content of the cellulose acylate in the resin component ispreferably greater than or equal to 60 mass %, is more preferablygreater than or equal to 70 mass %, is even more preferably greater thanor equal to 80 mass %, and is particularly preferably greater than orequal to 85 mass %. Furthermore, the upper limit of the content of thecellulose acylate is not particularly limited.

On the other hand, in addition to the cellulose acylate film asdescribed above, the optical film of the present invention may form amulti-layered configuration along with another layer in which thecellulose acylate is not contained as the resin component, or even whenresins other than the cellulose acylate are contained, the content ofthe cellulose acylate is less than 50 mass % of the total resincomponent. Examples of such a layer include layers specialized for aspecific function, and examples of the layer specialized for a specificfunction include a hard coat layer and the like.

In addition to the hard coat layer, examples of the layer specializedfor a specific function include an antiglare layer, a clear hard coatlayer, an antireflection layer, an antistatic layer, an antifoulinglayer, and the like. In a preferred aspect of the present invention,these layers are disposed on the hard coat layer.

The optical film of the present invention is useful for various purposessuch as a polarizing plate protective film and a surface protective filmarranged on an image display surface.

<<Cellulose Acylate Film>>

In the present invention, as described above, the cellulose acylate filmis formed of a film in which a ratio of cellulose acylate in a resinconstituent is greater than or equal to 50 mass %, and is the opticalfilm of the present invention in a narrow sense.

As described above, the cellulose acylate film may be a single layer, ora laminate film of two or more layers. When the cellulose acylate filmis a laminate film of two or more layers, it is preferable that thecellulose acylate film has a two-layer structure or a three-layerstructure, and it is more preferable that the cellulose acylate film hasthe three-layer structure. When the cellulose acylate film has thethree-layer structure, it is preferable that the cellulose acylate filmincludes a core layer of one layer (that is, the thickest layer, andhereinafter, also referred to as a base layer), and a skin layer A and askin layer B interposing the core layer therebetween. That is, it ispreferable that the cellulose acylate film of the present invention hasa three-layer structure of the skin layer B/the core layer/the skinlayer A. The skin layer B is a layer which is in contact with a metalsupport body described below at the time of manufacturing the celluloseacylate film by using solution film formation, and the skin layer A isan air interface layer on a side opposite to the metal support body.Furthermore, the skin layer A and the skin layer B are collectivelyreferred to as a skin layer (or a surface layer).

In the present invention, the cellulose acylate film contains celluloseacylate and at least one type of a compound denoted by General Formula(A) described below.

<Compound Denoted by General Formula (A)>

In General Formula (A), L represents an n-valent connecting group, nrepresents an integer of greater than or equal to 2, and A represents aheterocyclic group denoted by General Formula (I) described above.

In General Formula (I), R¹, R³, and R⁵ each independently represent ahydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, anaryl group, or a heteroaryl group. Here, any one of R¹, R³, and R⁵ isbonded to L.

Here, the expression “any one of R¹, R³, and R⁵ is bonded to L”indicates that, in a hydrogen atom or a defined substituent group of R¹,R³, and R⁵, a bond with respect to the hydrogen atom or one hydrogenatom of the substituent group is substituted with a direct bond. Forexample, when R¹, R³, and R⁵ are the hydrogen atom, the bond withrespect to the hydrogen atom becomes a single bond, and thus R¹, R³, andR⁵ are directly bonded to L, and when R¹, R³, and R⁵ are an alkyl group,a cycloalkyl group, an alkenyl group, an aryl group, and a heteroarylgroup, R¹, R³, and R⁵ become an alkylene group, a cycloalkylene group,an alkenylene group, an arylene group, and a heteroarylene group, andthus are bonded to L.

Any one of R¹, R³, and R⁵ is preferably used as a group bonded to L.

Each group of R¹, R³, and R⁵ may have a substituent group.

The substituent group is not particularly limited, and examples of thesubstituent group include an alkyl group (preferably an alkyl grouphaving 1 to 10 carbon atoms, for example, methyl, ethyl, isopropyl,t-butyl, pentyl, heptyl, i-ethyl pentyl, benzyl, 2-ethoxy ethyl,1-carboxy methyl, and the like), an alkenyl group (preferably an alkenylgroup having 2 to 20 carbon atoms, for example, vinyl, allyl, oleyl, andthe like), an alkynyl group (preferably an alkynyl group having 2 to 20carbon atoms, for example, ethynyl, 2-butynyl, phenyl ethynyl, and thelike), a cycloalkyl group (preferably a cycloalkyl group having 3 to 20carbon atoms, for example, cyclopropyl, cyclopentyl, cyclohexyl,4-methyl cyclohexyl, and the like), an aryl group (preferably an arylgroup having 6 to 26 carbon atoms, for example, phenyl, 1-naphthyl,4-methoxy phenyl, 2-chlorophenyl, 3-methyl phenyl, and the like), aheterocyclic group (preferably a heterocyclic group having 0 to 20carbon atoms, an oxygen atom, a nitrogen atom, and a sulfur atom arepreferable as a ring configuring hetero atom, a ring may be condensedwith a benzene ring or a hetero ring in a 5-membered ring or 6-memberedring, or a ring may be a saturated ring, an unsaturated ring, and anaromatic ring, for example, 2-pyridyl, 4-pyridyl, 2-imidazolyl,2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, and the like), an alkoxygroup (preferably an alkoxy group having 1 to 20 carbon atoms, forexample, methoxy, ethoxy, isopropyl oxy, benzyl oxy, and the like), anaryl oxy group (preferably an aryl oxy group having 6 to 26 carbonatoms, for example, phenoxy, 1-naphthyl oxy, 3-methyl phenoxy, 4-methoxyphenoxy, and the like),

an alkylthio group (preferably an alkylthio group having 1 to 20 carbonatoms, for example, methylthio, ethylthio, isopropylthio, benzylthio,and the like), an arylthio group (preferably an arylthio group having 6to 26 carbon atoms, for example, phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxy phenylthio, and the like), a sulfonyl group(preferably a sulfonyl group of alkyl or aryl, and preferably a sulfonylgroup having 1 to 20 carbon atoms, for example, methyl sulfonyl, ethylsulfonyl, benzene sulfonyl, toluene sulfonyl, and the like), an acylgroup (including an alkyl carbonyl group, an alkenyl carbonyl group, anaryl carbonyl group, and a heterocyclic carbonyl group, and preferablyan acyl group having carbon atoms of less than or equal to 20, forexample, acetyl, pivaloyl, acryloyl, methacryloyl, benzoyl, nicotinoyl,and the like), an alkoxy carbonyl group (preferably an alkoxy carbonylgroup having 2 to 20 carbon atoms, for example, ethoxy carbonyl, 2-ethylhexyl oxy carbonyl, and the like), an aryl oxy carbonyl group(preferably an aryl oxy carbonyl group having 7 to 20 carbon atoms, forexample, phenyl oxy carbonyl, naphthyl oxy carbonyl, and the like), anamino group (including an amino group, an alkyl amino group, an arylamino group, and a heterocyclic amino group, preferably an amino grouphaving 0 to 20 carbon atoms, for example, amino, N,N-dimethyl amino,N,N-diethyl amino, N-ethyl amino, anilino, 1-pyrrolidinyl, piperidino,morphonyl, and the like), a sulfone amide group (preferably a sulfoneamide group of alkyl or aryl, and preferably a sulfone amide grouphaving 0 to 20 carbon atoms, for example, N,N-dimethyl sulfone amide,N-phenyl sulfone amide, and the like), a sulfamoyl group (preferably asulfamoyl group of alkyl or aryl, and preferably a sulfamoyl grouphaving 0 to 20 carbon atoms, for example, N,N-dimethyl sulfamoyl,N-phenyl sulfamoyl, and the like), an acyl oxy group (preferably an acyloxy group having 1 to 20 carbon atoms, for example, acetyl oxy, benzoyloxy, and the like), a carbamoyl group (preferably a carbamoyl group ofalkyl or aryl, and preferably a carbamoyl group having 1 to 20 carbonatoms, for example, N,N-dimethyl carbamoyl, N-phenyl carbamoyl, and thelike), an acyl amino group (preferably an acyl amino group having 1 to20 carbon atoms, for example, acetyl amino, acryloyl amino, benzoylamino, nicotine amide, and the like), a cyano group, a hydroxy group, amercapto group, or a halogen atom (for example, a fluorine atom, achlorine atom, a bromine atom, an iodine atom, and the like).

The substituent groups described above may be further substituted withthe substituent groups described above. For example, a perfluoroalkylgroup such as trifluoromethyl, an aralkyl group, an alkyl groupsubstituted with an acyl group, and the like are included.

Furthermore, these substituent groups include not only the substituentgroups that each of the groups of R¹, R³, and R⁵ may have but also L,and are also applied to substituent groups of other compounds disclosedherein.

Here, when each of the groups of R¹, R³, and R⁵ has the substituentgroup, a bond with respect to one hydrogen atom of the substituent groupmay be substituted with a direct bond, and thus R¹, R³, and R⁵ may bebonded to L.

The number of carbon atoms of the alkyl group in R¹, R³, and R⁵ ispreferably 1 to 10, is more preferably 1 to 5, and is even morepreferably 1 to 3, and methyl or ethyl is particularly preferable. Here,in an alkyl group substituted with an aryl group, that is, an aralkylgroup, the number of carbon atoms of the aralkyl group is preferably 7to 20, is more preferably 7 to 12, and is even more preferably 7 to 10,and among them, benzyl and phenethyl are preferable, and the benzyl isparticularly preferable.

The number of carbon atoms of the cycloalkyl group in R¹, R³, and R⁵ ispreferably 3 to 10, is more preferably 4 to 8, and is even morepreferably 5 or 6. A specific example of the cycloalkyl group includescyclopropyl, cyclopentyl, and cyclohexyl, and the cyclohexyl isparticularly preferable.

The number of carbon atoms of the alkenyl group in R¹, R³, and R⁵ ispreferably 2 to 10, and is more preferably 2 to 5. For example, vinyland allyl are included.

The number of carbon atoms of the aryl group in R¹, R³, and R⁵ ispreferably 6 to 16, and is more preferably 6 to 12, and among them,phenyl and naphthyl are preferable, and the phenyl is particularlypreferable.

The number of carbon atoms of the heteroaryl group in R¹, R³, and R⁵ ispreferably 0 to 16, is more preferably 2 to 12, and is even morepreferably 3 to 12. In addition, it is preferable that a hetero ring ofthe heteroaryl group is a 5-membered ring or a 6-membered ring, and thehetero ring may be ring-condensed with a ring such as a benzene ring ora hetero ring. A nitrogen atom, an oxygen atom, and a sulfur atom arepreferable as the ring configuring hetero atom configuring a heteroring.

Examples of the hetero ring of the heteroaryl group include a thiophenering, a furan ring, a pyrrole ring, a pyrazole ring, an imidazole ring,a triazine ring, an oxazole ring, a thiazole ring, a pyridine ring, apyridazine ring, and a pyrimidine ring, and among them, the pyridinering is preferable.

Among the substituent groups described above that each of the groups ofR¹, R³, and R⁵ may have, the alkyl group, the cycloalkyl group, the arylgroup, the alkoxy group, the alkylthio group, and the halogen atom arepreferable, and the alkyl group, the cycloalkyl group, and the arylgroup are more preferable, and the alkyl group and the aryl group areeven more preferable.

The hydrogen atom, the alkyl group, the cycloalkyl group, the arylgroup, and the heteroaryl ring are preferable as R¹, R³, and R⁵, and thehydrogen atom, the alkyl group, the cycloalkyl group, and the aryl groupare more preferable as R¹, R³, and R⁵.

Among them, the alkyl group, the cycloalkyl group, and the aryl groupare preferable as R¹ and R³. On the other hand, the alkyl group and thecycloalkyl group are preferable as R⁵, and the aralkyl group and thecycloalkyl group are more preferable as R⁵.

n is preferably an integer of 2 to 5, is more preferably an integer of 2to 4, is even more preferably an integer of 2 or 3, and is particularlypreferably an integer of 2.

L represents an n-valent connecting group, a single bond, an alkylenegroup, a cycloalkylene group, an alkenylene group, an alkynylene group,an arylene group, a heteroarylene group, —O—, —S—, —NR— (R represents asingle bond, a hydrogen atom, an alkyl group, a cycloalkyl group, anaryl group, or an acyl group), —C(═O)—, —SO—, —SO₂—, an arenetriylgroup, a heteroarenetriyl group, or a connecting group formed bycombining thereof is preferable as L, and the single bond, the alkylenegroup, the cycloalkylene group, the arylene group, the heteroarylenegroup, —O—, —S—, —NR— (R represents a single bond, a hydrogen atom, analkyl group, a cycloalkyl group, an aryl group, or an acyl group), thearenetriyl group, the heteroarenetriyl group, or the connecting groupformed by combining thereof is more preferable as L, and the alkylenegroup, the cycloalkylene group, the arylene group, or the connectinggroup formed by combining thereof is even more preferable as L.

When L is a connecting group formed by combining a single bond, analkylene group, a cycloalkylene group, an alkenylene group, analkynylene group, an arylene group, a heteroarylene group, —O—, —S—,—NR— (R represents a single bond, a hydrogen atom, an alkyl group, acycloalkyl group, an aryl group, or an acyl group), —C(═O)—, —SO—,—SO₂—, an arenetriyl group, or a heteroarenetriyl group, examples of Linclude alkylene-arylene, alkylene-phenylene-alkylene,alkylene-heteroarylene-alkylene, alkylene-cycloalkylene-alkylene,phenylene-alkylene-phenylene, alkylene-O-alkylene, alkylene-NR-alkylene,alkylene-N(alkylene)₂, cycloalkylene-alkylene,cycloalkylene-alkylene-cycloalkylene,arylene-alkylene-arylene-alkylene-arylene,alkylene-arylene-arylene-alkylene, and the like.

In L, the number of atoms bonding at least two compounds denoted byGeneral Formula (I), that is, the number of atoms in the shortest bondis, preferably 1 to 15, is more preferably 1 to 10, is even morepreferably 1 to 9, and is particularly preferably 2 to 9.

Here, the number of atoms in the shortest bond indicates the number ofthe shortest atoms connecting R¹, R³, or R⁵ of the compound denoted byGeneral Formula (I), and for example, in the following compound, thenumber of atoms in the shortest bond is 5.

It is preferable that a shortest bond portion has a ring structure, anda cycloalkylene group, an arene ring which is an aromatic ring, or aheteroarene ring is preferable as a ring.

Here, a 5-membered ring or a 6-membered ring (a cyclopentane ring and acyclohexane ring) is preferable as the cycloalkylene group, and the6-membered ring is more preferable. Among them, cyclohexane-1,3-diyl,cyclohexane-1,4-diyl, and 1,5,5-trimethyl cyclohexane-1,3-diyl arepreferable.

Phenylene and naphthylene are preferable as the arylene group, and thephenylene is more preferable. Among the phenylenes, 1,3-phenylene and1,4-phenylene are preferable. Furthermore, among the naphthylenes,1,5-naphthylene is preferable.

A 5-membered ring or a 6-membered ring is preferable as a heteroarylring of the heteroarylene group, and a nitrogen atom, an oxygen atom,and a sulfur atom are preferable as the ring configuring hetero atom,and the nitrogen atom is more preferable.

Examples of the heteroaryl ring include a furan ring, a thiophene ring,a pyrrole ring, an oxazole ring, a thiazole ring, a pyrazole ring, atriazole ring, a pyridine ring, a pyrimidine ring, a pyrazine ring, atriazine ring, and a ring in which a benzene ring thereof isring-condensed (for example, a benzimidazole ring, a benzotriazole ring,and the like). For example, 2,6-pyridinyl is included.

Examples of the arenetriyl group include 1,3,5-benzene triyl, andexamples of the heteroarenetriyl group include pyridine-2,4,6-triyl.

A specific example of L includes the following connecting groups.However, the present invention is not limited thereto.

Here, a * portion indicates a portion which is bonded to any one of R¹,R³, and R⁵ in General Formula (I).

In the compound denoted by General Formula (A) in the present invention,the number of >NH partial structures in the molecules is preferably lessthan or equal to 3, is more preferably less than or equal to 2, is evenmore preferably less than or equal to 1, and is most preferably 0.Furthermore, the >NH partial structure indicates a partial structure inwhich a nitrogen atom configuring a ring structure in the moleculesdenoted by General Formula (I) is substituted with a hydrogen atom, thatis, a structure in which a substituent group of R¹ or R³; is a hydrogenatom.

In the compound denoted by General Formula (A) in the present invention,the total number of ring structures that L, R¹, R³, and R⁵ have ispreferably 1 to 6, is more preferably 2 to 6, and is even morepreferably 3 to 6.

The molecular weight of the compound denoted by General Formula (A) inthe present invention is preferably 250 to 2000, is more preferably 300to 1200, and is even more preferably 350 to 1000.

C log P of the compound denoted by General Formula (A) in the presentinvention is preferably −4.0 to 10.0, and is more preferably −2.0 to8.0. By obtaining such a C log P value, compatibility with respect tothe molecules of a cellulose acylate polymer becomes excellent.

Here, C log P will be described.

log P indicates common logarithm of a partition coefficient P, is aphysical property value which indicates how a certain chemical substanceis partitioned in the parallel in a two-phase system of oil (in general,1-octanol) and water as a quantitative numerical value, and is indicatedby the following expression.log P=log(C _(oil)/C _(water))

In the expression described above, C_(oil) indicates a molarconcentration in an oil phase of a certain chemical substance, andC_(water) indicates a molar concentration in a water phase of a certainchemical substance. When the value of log P is increased on a plus sideon the basis of 0, oil solubility increases, and when the absolute valueof log P is increased on a minus side, water solubility increases, log Phas a negative correlation with respect to the water solubility of thechemical substance, and is widely used as a parameter for estimatinghydrophilicity and hydrophobicity. In principle, the value is actuallymeasured in a partition test from the definition. However, the testitself is considerably difficult, and thus it is effective that thevalue is estimated from a structural formula.

For this reason, C log P is used as an estimation value of log P. C logP herein, a log P value estimation program developed by a Medchemproject of C. Hansch, A. Leo et al. of US Pomona University: C log P(strictly, a system of Daylight Chemical Information Systems, Inc.: a Clog P program incorporated in PC Models) is used. This program is basedon a fragment method of Hansch-Leo, a chemical structure is divided intofragments, and log P contributory portions allocated to the fragmentsare summed up, and thus C log P is estimated.

The theory with respect to C log P, for example, is specificallydisclosed in C. Hansch & A. Leo, Substituent Constants For CorrelationAnalysis in Chemistry and Biology (John Wiley & Sons), A. J. Leo.,Calculating log Poct from Structure., Chem. Rev., 93, 1281-1306 (1993),or the like.

A compound denoted by General Formula (A-1) or (A-2) described below ispreferable as the compound denoted by General Formula (A) in the presentinvention.

In General Formulas (A-1) and (A-2), R¹¹, R¹², R³¹, R³², R⁵¹, and R⁵²each independently represent a hydrogen atom, an alkyl group, acycloalkyl group, an alkenyl group, an aryl group, or a heteroarylgroup. X represents a single bond or a bivalent connecting group.

R¹¹ and R¹² are identical to R¹ in General Formula (I), and a preferredrange of R¹¹ and R¹² is also identical to that of R¹, R³¹ and R³² areidentical to R³ in General Formula (I), and a preferred range of R³¹ andR³² is also identical to R³. R⁵¹ and R⁵² are identical to R⁵ in GeneralFormula (I), and a preferred range of R⁵¹ and R⁵² is also identical tothat of R⁵.

The bivalent connecting group of X is identical to that of a case whereL in General Formula (A) is a bivalent connecting group, and a preferredrange of the bivalent connecting group of X is also identical to that ofthe case.

In General Formulas (A-1) and (A-2), R¹¹ and R¹², R³¹ and R³², and R⁵¹and R⁵² may be identical to each other or different from each other.

In the present invention, it is preferable that X is denoted by GeneralFormula (1) described below.*—CHR′—X′—CHR′—*  General Formula (1):

Here, * represents a portion connected to a hetero ring of GeneralFormula (A-1) or (A-2). R′ represents a hydrogen atom or a substituentgroup.

An alkyl group and an aryl group are preferable as the substituentgroup.

X′ is identical to that of a case where L of General Formula (A) is abivalent connecting group, and a preferred range of X′ is also identicalto that of the case. Furthermore, it is particularly preferable that X′is a ring structure.

Hereinafter, a specific example of the compound denoted by GeneralFormula (A) in the present invention is described, but the presentinvention is not limited thereto.

The compound denoted by General Formula (A) in the present invention,for example, is able to be synthesized in the following reaction scheme.

Here, R¹, R³, and R⁵ are R¹, R³, and R⁵ of General Formula (I), X is Xof General Formulas (A-1) and (A-2), and X¹ is a connecting group X¹ ofa case where X represents —CH₂—X¹—CH₂—.

Examples of a connection method in a 5-position include a method ofconnecting a compound having a barbituric acid skeleton in a 5-positionafter synthesizing the compound or a method of concurrently forming aplurality of barbituric acid skeletons by condensing a compound having aplurality of malonic acid derivative portions with a urea derivative.

It has been known that the compound having a barbituric acid skeleton isable to be synthesized by using an arbitrary synthesis method ofcondensing a urea derivative and a malonic acid derivative. Thebarbituric acid having two substituent groups on a nitrogen atom isobtained by heating N,N′-disubstituted urea and malonic acid chloride,or by mixing and heating N,N′-disubstituted urea and an activation agentsuch as a malonic acid and an acetic anhydride. For example, methodsdisclosed in Journal of the American Chemical Society, Vol. 61, P. 1015(1939), Journal of Medicinal Chemistry. Vol. 54, P. 2409 (2011),Tetrahedron Letters, Vol. 40, P. 8029 (1999), WO2007/150011A, and thelike are able to be preferably used.

In addition, the malonic acid used in the condensation may be anon-substitutional malonic acid or a malonic acid having a substituentgroup.

An addition reaction such as a nucleophilic substitution reaction (route2) with respect to halogenated alkyl or the like or a Michael additionreaction is able to be used as the connection method in a 5-position. Itis possible to synthesize a compound having methylene connection bycondensing an intermediate of the 5-position non-substitutionalbarbituric acid skeleton with formaldehyde (route 1).

In addition, a method is able to be preferably used in which analkylidene compound or an arylidene compound is generated by dehydratingand condensing the intermediate of the 5-position non-substitutionalbarbituric acid skeleton with aldehyde or ketone, and then a double bondis reduced (route 3).

For example, a reduction method using zinc is disclosed in TetrahedronLetters, Vol. 44, P. 2203 (2003), a reduction method using contactreduction is disclosed in Tetrahedron Letters, Vol. 42, P. 4103 (2001)or Journal of the American Chemical Society, Vol. 119, P. 12849 (1997),and a reduction method using NaBH₄ is disclosed in Tetrahedron Letters,Vol. 28, P. 4173 (1987) or the like. All of these methods are asynthesize method which is able to be preferably used when an aralkylgroup is in a 5-position or a cycloalkyl group is in a 5-position.

Examples of a connection method in a 1-position and a 3-position includea connection method using a substitution reaction or the like afterforming a barbituric acid skeleton and a method of concurrently forminga plurality of barbituric acid skeletons by condensing a compound havinga plurality of urea derivative portions with a malonic acid derivative.

A route 4 is a method of forming a barbituric acid skeleton aftersynthesizing a bis-type urea derivative by a reaction between isocyanateand amine.

Furthermore, a synthesis method of the compound denoted by GeneralFormula (A) used in the present invention is not limited to the methodsdescribed above.

The content of the compound denoted by General Formula (A) in theoptical film is not particularly limited. However, the content of thecompound denoted by General Formula (A) in the optical film ispreferably 0.1 parts by mass to 50 parts by mass, is more preferably 0.2parts by mass to 30 parts by mass, is even more preferably 0.3 parts bymass to 20 parts by mass, and is particularly preferably 0.3 parts bymass to 15 parts by mass, with respect to 100 parts by mass of celluloseacylate. According to such a content, hardness and suppression ofcoloration of the optical film which are the effects of the presentinvention are sufficiently expressed, and transparency of the film isalso maintained.

In addition, two or more types of compounds denoted by General Formula(A) may be contained in the optical film. In this case, it is preferablethat the total amount thereof is in the range described above.

<Cellulose Acylate>

In the present invention, one type of cellulose acylate which is a maincomponent of the cellulose acylate film may be used, or two or moretypes thereof may be used. For example, the cellulose acylate may becellulose acetate formed only of an acetyl group as an acyl substituentgroup, may be cellulose acylate having a plurality of different acylsubstituent groups, or may be a mixture of different cellulose acylates.

Examples of cellulose which is a raw material of the cellulose acylateused in the present invention include cotton linter, wood pulp (broadleaf wood pulp and conifer wood pulp), and the like, cellulose obtainedfrom any raw material cellulose is also able to be used, and accordingto a case, cellulose may be used by being mixed. For example, cellulosesdisclosed in Lecture of Plastic Materials (17) Cellulose-Based Resin (byMARUSAWA and UDA, The Nikkan Kogyo Shimbun, Ltd., Published in 1970) orJapan Institute of Invention and Innovation Disclosure 2001-1745 (Pages7 to 8) are able to be used as the raw material cellulose.

In the present invention, the acyl group of the cellulose acylate may beonly one type acyl group, or two or more types of acyl groups may beused. It is preferable that the cellulose acylate used in the presentinvention has an acyl group having carbon atoms of greater than or equalto 2 as a substituent group. The acyl group having carbon atoms ofgreater than or equal to 2 may be an aliphatic acyl group or an aromaticacyl group, but is not particularly limited. These acyl groups, forexample, are an alkyl carbonyl group, an alkenyl carbonyl group or anaromatic carbonyl group, an aromatic alkyl carbonyl group, and the likeof cellulose, and each further have a substituent group. Preferredexamples of the acyl group include acetyl, propionyl, butanoyl,heptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl,tetradecanoyl, hexadecanoyl, octadecanoyl, isobutanoyl, t-butanoyl,cyclohexane carbonyl, oleoyl, benzoyl, naphthyl carbonyl, cinnamoyl, andthe like. Among them, the acetyl, the propionyl, the butanoyl, thedodecanoyl, the octadecanoyl, the t-butanoyl, the oleoyl, the benzoyl,the naphthyl carbonyl, the cinnamoyl, and the like are more preferable,the acetyl, the propionyl, and the butanoyl are even more preferable.

It is preferable that the cellulose acylate used in the presentinvention has an acyl group having 2 to 4 carbon atoms as a substituentgroup. When two or more types of acyl groups are used, it is preferablethat, among them, one type is an acetyl group, and a propionyl group ora butyryl group is preferable as the acyl group having 2 to 4 carbonatoms used in the other. By using such cellulose acylate, a solutionhaving preferred solubility is able to be prepared, and in particular,in a non-chlorine-based organic solvent (for example, alcohols such asmethanol and ethanol), an excellent solution is able to be prepared.Further, a solution having low viscosity and excellent filtrationproperties is able to be prepared.

In the present invention, in particular, it is preferable that the acylgroup of the cellulose acylate is one type of acetyl group from aviewpoint of an excellent hardness enhancement effect of the compounddenoted by General Formula (A).

The cellulose acylate preferably used in the present invention will bedescribed in detail.

A β-1,4 bonding glucose unit configuring the cellulose has a freehydroxy group in a 2-position, in a 3-position, and in a 6-position. Thecellulose acylate is a polymer in which a part of all of these hydroxygroups is acylated by the acyl group.

An degree of acyl substitution indicates a degree of acylation of thehydroxy group in the cellulose, which is positioned in the 2-position,in the 3-position, and in the 6-position, and when all of the hydroxygroups in the 2-position, in the 3-position, and in the 6-position inall glucose units are acylated, the total degree of acyl substitution is3, and for example, when all of the hydroxy groups only in the6-position are acylated in all of the glucose units, the total degree ofacyl substitution is 1. Similarly, in all of the hydroxy groups in allof the glucose units, even when all of the hydroxy groups in any one ofthe 6-position and the 2-position are acylated in each of the glucoseunits, the total degree of acyl substitution is 1.

That is, the degree of acylation is denoted by a case where all of thehydroxy groups in glucose molecules are acylated to 3.

The details of a measurement method of the degree of acyl substitutionare based on a method disclosed in Carbohydrate. Res, by TEZUKA et al.273, 83-91 (1995) or a method defined in ASTM-D817-96.

The total degree of acyl substitution A of the cellulose acylate used inthe present invention is preferably greater than or equal to 1.5 andless than or equal to 3.0 (1.5≤A≤3.0), is more preferably 2.00 to 2.97,is even more preferably greater than or equal to 2.50 and less than2.97, and is particularly preferably 2.70 to 2.95.

In addition, in cellulose acetate using only the acetyl group as theacyl group of the cellulose acylate, the total degree of acetylsubstitution B is preferably greater than or equal to 2.0 and less thanor equal to 3 (2.0≤B≤3.0), is more preferably 2.0 to 2.97, is even morepreferably greater than or equal to 2.5 and less than 2.97, and is stillmore preferably greater than or equal to 2.55 and less than 2.97, isparticularly preferably 2.60 to 2.96, and is most preferably 2.70 to2.95.

Furthermore, in the compound denoted by General Formula (A) in thepresent invention, the effect is particularly expressed with respect tocellulose acylate in which the total degree of acetyl substitution B isgreater than 2.50.

When the cellulose acylate film of the optical film of the presentinvention is a laminated body (a multi-layered configuration), in thecellulose acylate film, the total degrees of acyl substitution A ofcellulose acylates in each of the layers may be identical to each otheror different from each other, and a plurality of cellulose acylates maybe mixed in one layer.

In the acylation of cellulose, when an acid anhydride or an acidchloride is used as an acylation agent, methylene chloride or an organicacid such as an acetic acid is used as an organic solvent which is areaction solvent.

When the acylation agent is the acid anhydride, a protonic catalyst suchas a sulfuric acid is preferably used as a catalyst, and when theacylation agent is the acid chloride (for example, CH₃CH₂COCl), a basiccompound is used as a catalyst.

An industrial synthesize method of mixed fatty acid ester which is themost general cellulose is a method in which cellulose is acylated by afatty acid (an acetic acid, a propionic acid, a valeric acid, and thelike) corresponding to an acetyl group and other acyl groups or a mixedorganic acid component including acid anhydrides thereof.

The cellulose acylate, for example, is able to be synthesized by using amethod disclosed in JP1998-45804A (JP-H10-45804A).

The film of the present invention, in particular, the cellulose acylatefilm used in the present invention, preferably contains the celluloseacylate in the amount of 5 mass % to 99 mass %, more preferably containsthe cellulose acylate in the amount of 20 mass % to 99 mass %, andparticularly preferably contains the cellulose acylate in the amount of50 mass % to 95 mass %, in the total solid content, from a viewpoint ofmoisture permeability.

<Other Additives>

In the optical film of the present invention, in particular, in thecellulose acylate film, additives such as a retardation adjusting agent(a retardation expression agent and a retardation reduction agent), aplasticizer such as a polycondensed ester compound (a polymer),polyvalent ester of polyvalent alcohol, phthalic acid ester, andphosphoric acid ester, an ultraviolet absorbent, an antioxidant, and amatting agent are able to be added.

Furthermore, herein, a compound group is described, for example, byusing “-based” such as a phosphoric acid ester-based compound. In thiscase, the “phosphoric acid ester-based compound” has the same meaning asthat of a phosphoric acid ester compound.

(Retardation Reduction Agent)

In the present invention, a phosphoric acid ester-based compound orcompounds other than an arbitrary non-phosphoric acid ester-basedcompound as the additive of the cellulose acylate film are able to bewidely adopted as the retardation reduction agent.

A high molecular retardation reduction agent is selected from aphosphoric acid polyester-based polymer, a styrene-based polymer, anacrylic polymer, and a copolymer thereof, and the acrylic polymer andthe styrene-based polymer are preferable. In addition, it is preferablethat at least one type of polymers having negative intrinsicbirefringence such as the styrene-based polymer and the acrylic polymeris included.

Examples of a low molecular weight retardation reduction agent which isthe compound other than the non-phosphoric acid ester-based compound areable to include the followings. The low molecular weight retardationreduction agent may be a solid or an oily substance. That is, themelting point or the boiling point thereof is not particularly limited.For example, ultraviolet absorbing materials having a melting point oflower than or equal to 20° C. and a melting point of higher than orequal to 20° C. are mixed, or similarly, deterioration preventive agentshaving a melting point of lower than or equal to 20° C. and a meltingpoint of higher than or equal to 20° C. are mixed. In addition, examplesof an infrared absorbing dye are able to include infrared absorbing dyesdisclosed in JP2001-194522A. In addition, as the time of adding thematerials, the materials may be added in any preparing step of acellulose acylate solution (dope), or the addition of the materials maybe performed by adding a step of adding and preparing the additive tothe final preparing step of a dope preparing step. In addition, theadded amount of each of the materials is not particularly limitedinsofar as the function is expressed.

The low molecular weight retardation reduction agent which is thecompound other than the non-phosphoric acid ester-based compound is notparticularly limited. Furthermore, the details thereof are disclosed inparagraphs 0066 to 0085 of JP2007-272177A.

A compound denoted by General Formula (1) disclosed in paragraphs 0066to 0085 of JP2007-272177A is able to be obtained by a condensationreaction between a sulfonyl chloride derivative and an amine derivativeas disclosed in the publication.

A compound denoted by General Formula (2) disclosed in JP2007-272177A isable to be obtained by a dehydrative condensation reaction betweencarboxylic acids and amines using a condensation agent (for example,dicyclohexyl carbodiimide (DCC) and the like), a substitution reactionbetween a carboxylic acid chloride derivative and an amine derivative,and the like.

It is more preferable that the retardation reduction agent is a Rthreduction agent from a viewpoint of realizing a preferred Nz factor.Here, Rth indicates retardation of the cellulose acylate film in a depthdirection. Among the retardation reduction agents, examples of the Rthreduction agent are able to include an acrylic polymer and astyrene-based polymer, low molecular compounds denoted by GeneralFormulas (3) to (7) disclosed in JP2007-272177A, and among them, theacrylic polymer and the styrene-based polymer are preferable, and theacrylic polymer is more preferable.

The added amount of the retardation reduction agent is preferably 0.01parts by mass to 30 parts by mass, is more preferably 0.1 parts by massto 20 parts by mass, and is particularly preferably 0.1 parts by mass to10 parts by mass, with respect to 100 parts by mass of celluloseacylate. By setting the added amount to be less than or equal to 30parts by mass, it is possible to improve compatibility with respect to acellulose-based resin, and it is possible to prepare a film havingexcellent transparency. When two or more types of retardation reductionagents are used, it is preferable that the total amount is in the rangedescribed above.

(Retardation Expression Agent)

In order to express a retardation value, the optical film of the presentinvention may contain at least one type of retardation expression agent.

The retardation expression agent is not particularly limited, andexamples of the retardation expression agent include a retardationexpression agent formed of a rod-like compound or a disk-like compound,or a compound exhibiting retardation expression properties among thenon-phosphoric acid ester-based compounds. As the rod-like compound orthe disk-like compound, a compound having at least two aromatic rings isable to be preferably used as the retardation expression agent.

The added amount of the retardation expression agent formed of therod-like compound is preferably 0.1 parts by mass to 30 parts by mass,and is more preferably 0.5 parts by mass to 20 parts by mass, withrespect to 100 parts by mass of cellulose acylate.

The disk-like compound has more excellent Rth retardation expressionproperties than the rod-like compound, and thus when particularly largeRth retardation is required, the disk-like compound is preferably used.Two or more types of retardation expression agents may be used together.

It is preferable that the retardation expression agent has the maximumabsorption wavelength in a wavelength region of 250 nm to 400 nm, and itis preferable that the retardation expression agent does notsubstantially have absorption in a visible region.

The details of the retardation expression agent are disclosed in Page 49of Journal of Technical Disclosure 2001-1745.

The added amount of the retardation expression agent formed of thedisk-like compound is preferably 0.1 parts by mass to 30 parts by mass,and is more preferably 0.5 parts by mass to 20 parts by mass, withrespect to 100 parts by mass of cellulose acylate.

The added amount of the disk-like compound contained in the retardationexpression agent is preferably less than 3 parts by mass, is morepreferably less than 2 parts by mass, and is particularly preferablyless than 1 part by mass, with respect to 100 parts by mass of celluloseacylate.

[Plasticizer (Hydrophobizing Agent)]

In the optical film, in particular, in the cellulose acylate film, whena plasticizer is contained in the cellulose acylate film, moisturecontent or moisture permeability of the cellulose acylate filmdecreases, and a hydrolysis reaction of the cellulose acylate due tomoisture in the cellulose acylate film is suppressed. Further, theplasticizer suppresses diffusion of the additives from the celluloseacylate film to a polarizer layer under high temperature and highhumidity conditions, and thus it is possible to reduce deterioration ofpolarizer performance.

The compound denoted by General Formula (A) in the present invention iscontained in the optical film, in particular, in the cellulose acylatefilm, and thus is able to be used as the plasticizer. That is, an effectof enhancing durability including control of a glass transitiontemperature and a reduction in the moisture content and the moisturepermeability as described above is able to be obtained, and hardness ofthe cellulose acylate film is also able to be high. Further, even whenthe compound denoted by General Formula (A) in the present invention isused together with other general-purpose plasticizers, the hardnessimprovement effect is able to be obtained, and thus a plurality ofplasticizers may be contained together in the optical film and in thecellulose acylate film.

Furthermore, it is preferable that the optical film of the presentinvention contains at least one type of plasticizer.

In the present invention, among the plasticizers used together, amulti-ester-based plasticizer is preferable in which ester groups arepositionally close to each other and clogged with each other inmolecules. Specifically, examples of the multi-ester-based plasticizerinclude a polycondensed ester compound (hereinafter, referred to as apolycondensed ester-based plasticizer), a polyvalent ester compound ofpolyvalent alcohol (hereinafter, referred to as a polyvalent alcoholester-based plasticizer), and a carbohydrate compound (hereinafter,referred to as a carbohydrate derivative-based plasticizer). In thepresent invention, these compounds are excellent for expressing theplasticizer effect as described above.

Hereinafter, the plasticizer used in the present invention will bedescribed.

(Polycondensed Ester-Based Plasticizer)

The polycondensed ester-based plasticizer is obtained by polycondensinga bivalent carboxylic acid compound and a diol compound.

It is preferable that the polycondensed ester-based plasticizer isobtained by polycondensing at least one type of dicarboxylic aciddenoted by General Formula (a) described below and at least one type ofdiol denoted by General Formula (b) described below.

In General Formulas (a) and (b), Y represents a bivalent aliphatic grouphaving 2 to 18 carbon atoms, a bivalent aromatic group having 6 to 18carbon atoms, or a bivalent hetero ring having 2 to 18 carbon atoms, andZ represents a bivalent aliphatic group having 2 to 8 carbon atoms.Here, the bivalent aliphatic group having 2 to 8 carbon atoms may be astraight-chain bivalent aliphatic group or a branched bivalent aliphaticgroup.

Examples of the bivalent carboxylic acid compound denoted by GeneralFormula (a) include, as described above, an aliphatic carboxylic acidand an aromatic carboxylic acid or a heterocyclic carboxylic acid, andthe aliphatic carboxylic acid or the aromatic carboxylic acid ispreferable.

On the other hand, examples of the diol compound also include anaromatic compound or a heterocyclic compound in addition to thealiphatic compound denoted by General Formula (b) described above.

Among them, a polycondensed ester-based plasticizer formed of at leastone type of dicarboxylic acid having aromatic ring (also referred to asan aromatic dicarboxylic acid) and at least one type of aliphatic diolin which the average number of carbon atoms is 2.5 to 8.0 is preferable.In addition, a polycondensed ester-based plasticizer formed of a mixtureof an aromatic dicarboxylic acid and at least one type of aliphaticdicarboxylic acid, and at least one type of aliphatic diol in which theaverage number of carbon atoms is 2.5 to 8.0 is also preferable.

The number average molecular weight of the polycondensed ester-basedplasticizer is preferably 500 to 2000, is more preferably 600 to 1500,and is even more preferably 700 to 1200. When the number averagemolecular weight of the polycondensed ester-based plasticizer is greaterthan or equal to 500, and is preferably greater than or equal to 600,volatility decreases, and a defect in film or step contamination due tovolatilization under high temperature conditions at the time ofstretching the cellulose acylate film is excellently suppressed.

In addition, when the number average molecular weight of thepolycondensed ester-based plasticizer is less than or equal to 2000,compatibility with respect to the cellulose acylate increases, and bleedout at the time of film formation and at the time of heating andstretching is excellently suppressed.

When a mixture of an aromatic dicarboxylic acid and an aliphaticdicarboxylic acid is used as a dicarboxylic acid component, the averagenumber of carbon atoms in the dicarboxylic acid component is preferably5.5 to 10.0, and is more preferably 5.6 to 8.0.

When the average number of carbon atoms is greater than or equal to 5.5,a polarizing plate having excellent durability is able to be obtained.When the average number of carbon atoms is less than or equal to 10.0,the compatibility with respect to the cellulose acylate becomesexcellent, and bleed out during the film formation of the celluloseacylate film is excellently suppressed.

Examples of the aromatic dicarboxylic acid which is able to be used forsynthesizing the polycondensed ester-based plasticizer are able toinclude a phthalic acid, a terephthalic acid, an isophthalic acid, a1,5-naphthalene dicarboxylic acid, a 1,4-naphthalene dicarboxylic acid,a 1,8-naphthalene dicarboxylic acid, a 2,8-naphthalene dicarboxylicacid, a 2,6-naphthalene dicarboxylic acid, and the like. Among them, thephthalic acid, the terephthalic acid, and the 2,6-naphthalenedicarboxylic acid are preferable, the phthalic acid and the terephthalicacid are more preferable, and the terephthalic acid is even morepreferable.

The polycondensed ester-based plasticizer obtained from the diolcompound and the dicarboxylic acid including the aliphatic dicarboxylicacid contains an aliphatic dicarboxylic acid residue.

Examples of the aliphatic dicarboxylic acid synthesizing thepolycondensed ester-based plasticizer include an oxalic acid, a malonicacid, a succinic acid, a maleic acid, a fumaric acid, a glutaric acid,an adipic acid, a pimelic acid, a suberic acid, an azelaic acid, asebacic acid, a dodecane dicarboxylic acid, a 1,4-cyclohexanedicarboxylic acid, and the like.

Examples of the diol synthesizing the polycondensed ester-basedplasticizer include an aromatic diol and an aliphatic diol, and in thepresent invention, it is preferable that the polycondensed ester-basedplasticizer is synthesized by using at least the aliphatic diol.

It is preferable that the polycondensed ester-based plasticizer containsan aliphatic diol residue in which the average number of carbon atoms is2.5 to 7.0, and it is more preferable that the polycondensed ester-basedplasticizer contains an aliphatic diol residue in which the averagenumber of carbon atoms is 2.5 to 4.0.

When the average number of carbon atoms in the aliphatic diol residue isless than 7.0, the compatibility with respect to the cellulose acylateis enhanced, and the bleed out, an increase in heating loss of thecompound, and a planar defect which is considered to be caused by thestep contamination at the time of performing web drying with respect tothe cellulose acylate are excellently suppressed. In addition, when theaverage number of carbon atoms in the aliphatic diol residue is greaterthan or equal to 2.5, the synthesis is easily performed.

Alkyl diols or alicyclic diols are preferable as the aliphatic diol usedfor synthesizing the polycondensed ester-based plasticizer, and forexample, ethylene glycol, 1,2-propane diol, and 1,3-propane diol arepreferable, and the ethylene glycol and the 1,2-propane diol are morepreferable.

The terminal of the polycondensed ester-based plasticizer may be left asdiol or a carboxylic acid (that is, a polymer long-chain terminal is —OHor CO₂H) without being sealed, and may be subjected to so-calledterminal sealing by allowing monocarboxylic acids or monoalcohols toreact therewith. Furthermore, by sealing the terminal of thepolycondensed ester-based plasticizer, it is possible to obtain acellulose acylate film in which a state at a normal temperature israrely turned into a solid state, handling properties become excellent,and humidity stability and durability of a polarizing plate areexcellent.

Polycondensed ester-based plasticizers J-1 to J-38 disclosed inparagraphs 0062 to 0064 of JP2012-234159A are preferable as thepolycondensed ester-based plasticizer.

(Polyvalent Alcohol Ester-Based Plasticizer)

The polyvalent alcohol ester-based plasticizer used in the presentinvention is an ester in which an alcohol portion is derived frompolyvalent alcohol having two or more hydroxy groups. In addition to thehydroxy group, alcohol in which saturated hydrocarbon which may beseparated through an ether bond is substituted with two or more hydroxygroups is preferable as alcohol of the alcohol portion.

The polyvalent alcohol which is the raw material of the polyvalentalcohol ester-based plasticizer is denoted by General Formula (c)described below.Rα—(OH)m  General Formula (c)

In General Formula (c), Rα represents an m-valent organic group, and mrepresents a positive integer of greater than or equal to 2.

The number of carbon atoms in the polyvalent alcohol is preferablygreater than or equal to 5, and is more preferably 5 to 20.

Examples of such polyvalent alcohol include sugar alcohol or glycols.

Specifically, triethylene glycol, tetraethylene glycol, dipropyleneglycol, tripropylene glycol, sorbitol, trimethylol propane, and xylitolare preferable.

An acid portion derived from a monocarboxylic acid is preferable as anacid portion of the polyvalent alcohol ester (an acyl portion of ester).Examples of such an acid include an aliphatic monocarboxylic acid, analicyclic monocarboxylic acid, and an aromatic monocarboxylic acid, andit is preferable that the alicyclic monocarboxylic acid and the aromaticmonocarboxylic acid are used from a viewpoint of improving moisturepermeability and retention properties.

The number of carbon atoms in the aliphatic monocarboxylic acid ispreferably 1 to 32, is more preferably 1 to 20, and is particularlypreferably 1 to 10. It is preferable that an acetic acid is containedfrom a viewpoint of increasing the compatibility with respect to thecellulose derivative, and it is also preferable that the acetic acid andother monocarboxylic acids are used by being mixed.

Preferred examples of the aliphatic monocarboxylic acid include asaturated fatty acid such as an acetic acid, a propionic acid, a butyricacid, a valeric acid, a caproic acid, an enanthic acid, a caprylic acid,a pelargonic acid, a capric acid, a 2-ethyl-hexane carboxylic acid, anundecylic acid, a lauric acid, a tridecylic acid, a myristic acid, apentadecylic acid, a palmitic acid, a heptadecylic acid, a stearic acid,a nonadecanoic acid, an arachic acid, a behenic acid, a lignoceric acid,a cerotic acid, a heptacosanoic acid, a montanic acid, a melissic acid,and a lacceric acid, an unsaturated fatty acid such as an undecylenicacid, an oleic acid, a sorbic acid, a linoleic acid, a linolenic acid,and an arachidonic acid, and the like.

Preferred examples of the alicyclic monocarboxylic acid include acyclopentane carboxylic acid, a cyclohexane carboxylic acid, acyclooctane carboxylic acid, or a derivative thereof.

Preferred examples of the aromatic monocarboxylic acid include anaromatic monocarboxylic acid in which an alkyl group is introduced intoa benzene ring of a benzoic acid, such as a benzoic acid and a toluicacid, biphenyl carboxylic acid, an aromatic monocarboxylic acid havingtwo or more benzene rings, such as a naphthalene carboxylic acid and atetralin carboxylic acid, or a derivative thereof, and the benzoic acidis particularly preferable.

The molecular weight of the polyvalent alcohol ester-based plasticizeris not particularly limited, but is preferably 300 to 3000, and is morepreferably 350 to 1500. It is preferable that the polyvalent alcoholester-based plasticizer has a large molecular weight from a viewpoint ofexcellently suppressing volatilization from the optical film, and it ispreferable that the polyvalent alcohol ester-based plasticizer has asmall molecular weight from a viewpoint of the moisture permeability andthe compatibility with respect to the cellulose derivative.

For example, a compound disclosed in paragraphs 0045 to 0049 ofJP2012-234159A is preferable as the polyvalent alcohol ester-basedplasticizer, and is preferably incorporated herein as a part.

(Carbohydrate Derivative-Based Plasticizer)

Examples of the carbohydrate derivative-based plasticizer includederivatives of carbohydrate having monosaccharide or 2 to 10monosaccharide units, and among them, acylated carbohydrate ispreferable.

Examples of the carbohydrate having monosaccharide or 2 to 10monosaccharide units preferably include ribose, arabinose, xylose,lyxose, glucose, fructose, mannose, galactose, trehalose, maltose,cellobiose, lactose, sucrose, sucralose, α-cyclodextrin, β-cyclodextrin,γ-cyclodextrin, δ-cyclodextrin, xylitol, and sorbitol, more preferablyinclude the arabinose, the xylose, the glucose, the fructose, themannose, the galactose, the maltose, the cellobiose, the sucrose, theβ-cyclodextrin and the γ-cyclodextrin, and particularly preferablyinclude the xylose, the glucose, the fructose, the mannose, thegalactose, the maltose, the cellobiose, the sucrose, the xylitol, andthe sorbitol.

Preferred examples of the carbohydrate derivative-based plasticizerinclude maltose octaacetate, cellobiose octaacetate, sucroseoctaacetate, xylose tetrapropionate, glucose pentapropionate, fructosepentapropionate, mannose pentapropionate, galactose pentapropionate,maltose octapropionate, cellobiose octapropionate, sucroseoctapropionate, xylose tetrabenzoate, glucose pentabenzoate, fructosepentabenzoate, mannose pentabenzoate, galactose pentabenzoate, maltoseoctabenzoate, cellobiose octabenzoate, sucrose octabenzoate, xylitolpentabenzoate, and sorbitol hexabenzoate.

A carbohydrate derivative-based plasticizer having a pyranose structureor a furanose structure is preferable as the carbohydratederivative-based plasticizer.

A compound disclosed in paragraphs 0030 to 0039 of JP2012-234159A ispreferable as the carbohydrate derivative-based plasticizer.

Furthermore, in the present invention, the contents disclosed inparagraphs 0026 to 0068 of JP2012-234159A are preferably applied to theplasticizer, and the contents disclosed in the paragraphs describedabove are preferably incorporated herein as a part.

The added amount of the plasticizer is preferably 0.1 mass % to 50 mass% with respect to 100 parts by mass of the cellulose acylate. Apreferred added amount of the plasticizer is 1 mass % to 20 mass %, whenthe added amount of the plasticizer is greater than or equal to 1 mass%, a durability enhancement effect of a polarizer is easily obtained,and when the added amount of the plasticizer is less than or equal to 20mass %, the bleed out hardly occurs. Further, the added amount ispreferably 2 mass % to 15 mass %, and is particularly preferably 4 mass% to 15 mass %. Furthermore, two or more types of plasticizers may beadded. Even when two or more types of plasticizers are added, a specificexample and a preferred range of the added amount are identical to thosedescribed above.

A timing of adding the plasticizer to the cellulose acylate film is notparticularly limited insofar as the plasticizer is added at the time offorming the film. For example, the plasticizer may be added at the timeof synthesizing the cellulose acylate, or the plasticizer may be mixedwith the cellulose acylate at the time of preparing a dope.

(Antioxidant)

It is preferable that the optical film of the present invention containsan antioxidant. The antioxidant is able to be added to the celluloseacylate solution. In the present invention, an arbitrary antioxidant,for example, a phenol-based antioxidant or a hydroquinone-basedantioxidant such as 2,6-di-t-butyl-4-methyl phenol,4,4′-thiobis-(6-t-butyl-3-methyl phenol), 1,1′-bis(4-hydroxyphenyl)cyclohexane, 2,2′-methylene bis(4-ethyl-6-t-butyl phenol),2,5-di-t-butyl hydroquinone, andpentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxy phenyl) propionate]is able to be added. Further, it is preferable that a phosphorus-basedantioxidant such as tris(4-methoxy-3,5-diphenyl)phosphite, tris(nonylphenyl)phosphite, tris(2,4-di-t-butyl phenyl)phosphite,bis(2,6-di-t-butyl-4-methyl phenyl)pentaerythritol diphosphite, andbis(2,4-di-t-butyl phenyl)pentaerythritol diphosphite is used.

The added amount of the antioxidant is preferably 0.05 parts by mass to5.0 parts by mass with respect to 100 parts by mass of the celluloseacylate.

(Ultraviolet Absorbent)

The optical film of the present invention may contain an ultravioletabsorbent from a viewpoint of preventing deterioration of a polarizingplate, a liquid crystal, and the like. The ultraviolet absorbent is ableto be added to the cellulose acylate solution. In the present invention,an ultraviolet absorbent having low absorbancy in visible light having awavelength of greater than or equal to 400 nm is preferably used as theultraviolet absorbent from a viewpoint of excellent absorption capacityin ultraviolet light having a wavelength of less than or equal to 370 nmand excellent liquid crystal display properties. Examples of theultraviolet absorbent preferably used in the present invention include ahindered phenol-based compound, a hydroxy benzophenone-based compound, abenzotriazole-based compound, a salicylic acid ester-based compound, abenzophenone-based compound, a cyanoacrylate-based compound, a nickelcomplex salt-based compound, and the like.

Examples of the hindered phenol-based compound include2,6-di-t-butyl-p-cresol,pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxy phenyl)propionate], N,N′-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamide),1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxy benzyl)benzene,tris-(3,5-di-t-butyl-4-hydroxy benzyl)-isocyanurate, and the like.

Examples of the benzotriazole-based compound include2-(2′-hydroxy-5′-methyl phenyl)benzotriazole, 2,2-methylenebis[4-(1,1,3,3-tetramethyl butyl)-6-(2H-benzotriazol-2-yl)phenol],(2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine, triethyleneglycol-bis[3-(3-t-butyl-5-methyl-4-hydroxy phenyl) propionate],N,N′-hexamethylene bis(3,5-di-t-butyl-4-hydroxy-hydrocinnamide),1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxy benzyl)benzene,2-(2′-hydroxy-3′,5′-di-t-butyl phenyl)-5-chlorobenzotriazole,2-(2′-hydroxy-3′,5′-di-t-amyl phenyl)-5-chlorobenzotriazole,2,6-di-t-butyl-p-cresol,pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxy phenyl)propionate], and the like.

The added amount of the ultraviolet absorbent is preferably 1% to 1.0%in a mass ratio in the total solid content of the cellulose acylatefilm, and is further preferably 10 ppm to 1000 ppm.

(Matting Agent)

The optical film of the present invention may further contain a mattingagent from a viewpoint of film slipperiness and stable manufacturing.The matting agent may be a matting agent of an inorganic compound, ormay be a matting agent of an organic compound.

An inorganic compound containing silicon (for example, silicon dioxide,calcined calcium silicate, hydrated calcium silicate, aluminum silicate,magnesium silicate, and the like), titanium oxide, zinc oxide, aluminumoxide, barium oxide, zirconium oxide, strontium oxide, antimony oxide,tin oxide, tin-antimony oxide, calcium carbonate, talc, clay, calcinedkaolin, calcium phosphate, and the like are preferable as the mattingagent of the inorganic compound, and the inorganic compound containingsilicon or the zirconium oxide is more preferable. The silicon dioxideis particularly preferable from a viewpoint of capable of reducingturbidity of the cellulose acylate film.

For example, commercial products with product names such as AerosilR972, Aerosil R974, Aerosil R812, Aerosil 200, Aerosil 300, AerosilR202, Aerosil OX50, and Aerosil TT600 (all are manufactured by NipponAerosil Co., Ltd.) are able to be used as fine particles of the silicondioxide. For example, commercially available products with product namessuch as Aerosil R976 and Aerosil R811 (all are manufactured by NipponAerosil Co., Ltd.) are able to be used as the fine particles of thezirconium oxide.

For example, a polymer such as a silicone resin, a fluorine resin, andan acrylic resin is preferable as the matting agent of the organiccompound, and among them, the silicone resin is preferable. Among thesilicone resins, a silicone resin having a three-dimensional mesh-likestructure is particularly preferable, and for example, commerciallyavailable products with product names such as Tospearl 103, Tospearl105, Tospearl 108, Tospearl 120, Tospearl 145, Tospearl 3120, andTospearl 240 (all are manufactured by Momentive Performance MaterialsInc.) are able to be used.

When such a matting agent is added to the cellulose acylate solution, amethod of adding the matting agent is not particularly limited insofaras a desired cellulose acylate solution is able to be obtained by usingany method. For example, the additive may be contained in a step ofmixing the cellulose acylate and a solvent, or the additive may be addedafter preparing a mixed solution of the cellulose acylate and a solvent.

Further, a so-called adding immediately before casting method may beused in which the additive is added and mixed immediately before castinga dope, and the mixing is performed by disposing screw type kneadersonline. Specifically, a static mixer such as an inline mixer ispreferable. In addition, a static mixer SWJ (a Toray static in-tubemixer Hi-Mixer) (manufactured by Toray Engineering Co., Ltd.) ispreferable as the inline mixer.

Furthermore, in order to eliminate concentration unevenness, aggregationof particles, and the like in the inline adding, a manufacturing methodof a cellulose acylate film is disclosed in JP2003-053752A in which adistance L between an adding nozzle tip end mixing a dope of a main rawmaterial with an additive liquid having a different composition and astarting end of an inline mixer is set to be less than or equal to 5times an inner diameter d of a tube for a main raw material, and thusconcentration unevenness, aggregation of matting particles, and the likeare eliminated. A more preferred aspect is disclosed in which a distance(L) between a tip opening portion of a supply nozzle for an additiveliquid having a composition different from that of a dope of a main rawmaterial and a starting end of an inline mixer is set to be less than orequal to 10 times an inner diameter (d) of the tip opening portion ofthe supply nozzle, and an inline mixer is a static non-stirring typein-tube mixer or a dynamic stirring type in-tube mixer. Morespecifically, it is disclosed that a flow ratio of a dope of a main rawmaterial of a cellulose acylate film/an inline additive liquid is 10/1to 500/1, and is preferably 50/1 to 200/1.

Further, a method of adding an additive is disclosed in JP2003-014933Aof which an object is to provide a retardation film in which bleed outof the additive is reduced, a peeling phenomenon between layers iseliminated, and slipperiness and transparency are excellent.Specifically, it is disclosed that the additive may be added into adissolving vessel, or the additive or a solution in which the additivesare dissolved or dispersed may be added into the dope during liquidfeeding between the dissolving vessel and a cocasting die, and in thelatter case, it is preferable that mixing means such as a static mixeris disposed in order to increase mixing properties.

It is particularly preferable that the matting agent is contained in thecellulose acylate film in the ratio of 0.05 mass % to 1.0 mass %.According to such a value, when haze of the cellulose acylate film doesnot increase, and the cellulose acylate film is actually used in an LCD,the value described above contributes to suppression of problems such asa decrease in contrast, the occurrence of a bright spot, and the like.In addition, it is possible to realize creaking resistance and scratchresistance. From such a viewpoint, it is particularly preferable thatthe matting agent is contained in the cellulose acylate film in theratio of 0.05 mass % to 1.0 mass %.

<Physical Properties of Cellulose Acylate Film>

(Hardness)

As surface hardness, it is preferable that knoop hardness according to aknoop method using a knoop indenter is high, and it is also preferablethat pencil hardness is high. The knoop hardness is able to be measuredby using a hardness meter including a knoop indenter in an indenter, forexample. “Fischer Scope H100Vp type hardness meter” manufactured byFischer Instruments K. K.

The pencil hardness, for example, is able to be evaluated by using apencil for a test defined in JIS-S6006 according to a pencil hardnessevaluation method defined in JIS-K5400.

The compound denoted by General Formula (A) in the present invention isable to increase hardness of the cellulose acylate film such as knoophardness. Furthermore, the hardness of the cellulose acylate film isable to be adjusted according to the type or the content of the compounddenoted by General Formula (A).

[Modulus of Elasticity (Modulus of Tension Elasticity)]

It is preferable that the cellulose acylate film practically exhibitssufficient modulus of elasticity (modulus of tension elasticity). Therange of the modulus of elasticity is not particularly limited. However,the range of the modulus of elasticity is preferably 1.0 GPa to 7.0 GPa,and is more preferably 2.0 GPa to 6.5 GPa from a viewpoint ofmanufacturing suitability and handling properties. The compound denotedby General Formula (A) in the present invention is added into thecellulose acylate film, and thus the cellulose acylate film ishydrophobized and the modulus of elasticity is improved, and theseproperties are advantages of the present invention.

(Photoelastic Coefficient)

The absolute value of a photoelastic coefficient of the celluloseacylate film is preferably less than or equal to 8.0×10⁻¹² m²/N, is morepreferably less than or equal to 6×10⁻¹² m²/N, and is even morepreferably less than or equal to 5×10⁻¹² m²/N. The photoelasticcoefficient of the cellulose acylate film decreases, and thus when theoptical film of the present invention including the cellulose acylatefilm is incorporated in a liquid crystal display device as a polarizingplate protective film, it is possible to suppress the occurrence ofunevenness under hygrothermal conditions. The photoelastic coefficient,unless otherwise specifically stated, is calculated by being measuredaccording to the following methods.

The lower limit value of modulus of photoelasticity is not particularlylimited. Furthermore, it is practical that the lower limit value ofmodulus of photoelasticity is greater than or equal to 0.1×10⁻¹² m²/N.

The cellulose acylate film is cut to have a size of 3.5 cm×12 cm, andthe photoelastic coefficient is calculated from a slope of a straightline of a change in retardation (Re is measured by using an ellipsometer(M150 [product name], manufactured by Jasco Corporation), and Re withrespect to stress) at each load of no load, 250 g, 500 g, 1000 g, and1500 g.

(Moisture Content)

The moisture content of the cellulose acylate film is able to beevaluated by measuring an equilibrium moisture content at constanttemperature and humidity. The equilibrium moisture content is calculatedby measuring the moisture amount of a sample which reaches equilibriumafter being placed for 24 hours at the constant temperature and humiditydescribed above using a Karl Fischer method, and by dividing a moistureamount (g) by a sample mass (g).

The moisture content of the cellulose acylate film at a temperature of25° C. and relative humidity of 80% is preferably less than or equal to5 mass %, is more preferably less than or equal to 4 mass %, and is evenmore preferably less than 3 mass %. The moisture content of thecellulose acylate film decreases, and thus when the optical film of thepresent invention including the cellulose acylate film is incorporatedin the liquid crystal display device as the polarizing plate protectivefilm, it is possible to suppress the occurrence of display unevenness ofthe liquid crystal display device under hygrothemal conditions. Thelower limit value of the moisture content is not particularly limited.Furthermore, it is practical that the lower limit value of the moisturecontent is greater than or equal to 0.1 mass %.

(Moisture Permeability)

The moisture permeability of the cellulose acylate film is able to beevaluated by measuring the mass of water vapor per 24 hours passingthrough the sample in an atmosphere of a temperature of 40° C. andrelative humidity of 90% on the basis of a moisture permeability test (acup method) of JIS Z0208, and by converting the mass of the water vaporper 24 hours into the mass of the water vapor passing through for 24hours per a sample area of 1 m².

The moisture permeability of the cellulose acylate film is preferably500 g/m²·day to 2000 g/m²·day, is more preferably 900 g/m²·day to 1300g/m²·day, and is particularly preferably 1000 g/m² day to 1200 g/m²·day.

(Haze)

The haze of the cellulose acylate film is preferably less than or equalto 1%, is more preferably less than or equal to 0.7%, and isparticularly preferably less than or equal to 0.5%. By setting the hazeto be less than or equal to the upper limit value described above,advantages such as a further increase in transparency of the celluloseacylate film and ease of use as an optical film are obtained. The haze,unless otherwise specifically stated, is calculated by being measuredaccording to the following methods. The lower limit value of the haze isnot particularly limited. Furthermore, it is practical that the lowerlimit value of the haze is greater than or equal to 0.001%.

A cellulose acylate film of 40 mm×80 mm is measured under an environmentof a temperature of 25° C. and relative humidity of 60% by using ahazemeter (HGM-2DP, manufactured by Suga test Instruments Co., Ltd.)according to JIS K7136.

(Film Thickness)

The average film thickness of the cellulose acylate film is preferably10 μm to 100 μm, is more preferably 15 μm to 80 μm, and is even morepreferably 15 μm to 70 μm. By setting the average film thickness of thecellulose acylate film to be greater than or equal to 15 μm, handlingproperties at the time of preparing a web-like film are improved, andthus setting the average film thickness of the cellulose acylate film tobe greater than or equal to 15 μm is preferable. In addition, by settingthe average film thickness of the cellulose acylate film to be less thanor equal to 70 μm, it is easy to deal with a humidity change, and it iseasy to maintain optical properties.

In addition, when the cellulose acylate film has a laminated structureof three or more layers, the film thickness of the core layer ispreferably 3 μm to 70 μm, and is more preferably 5 μm to 60 μm, and thefilm thickness of the skin layer A and the skin layer B is preferably0.5 μm to 20 μm, is more preferably 0.5 μm to 10 μm, and is particularlypreferably 0.5 μm to 3 μm.

(Width)

The width of the cellulose acylate film is preferably 700 mm to 3000 mm,is more preferably 1000 mm to 2800 mm, and is particularly preferably1300 mm to 2500 mm.

<Manufacturing Method of Cellulose Acylate Film>

A manufacturing method of the cellulose acylate film of the presentinvention is not particularly limited. Furthermore, it is preferablethat the cellulose acylate film of the present invention is manufacturedby using a melting film forming method or a solution casting method, andit is more preferable that the cellulose acylate film of the presentinvention is manufactured by using the solution casting method (asolvent cast method). A manufacturing example of the cellulose acylatefilm using the solvent cast method is able to refer to the specificationof each of U.S. Pat. Nos. 2,336,310B, 2,367,603B, 2,492,078B,2,492,977B, 2,492,978B, 2,607,704B, 2,739,069B, and 2,739,070B, thespecification of each of GB640731B and GB736892B, and the publication ofeach of JP1970-4554B (JP-S45-4554B), JP1974-5614B (JP-S49-5614B),JP1985-176834A (JP-S60-176834A), JP1985-203430A (JP-S60-203430A),JP-1987-115035A (JP-S62-115035A), and the like. In addition, thecellulose acylate film may be subjected to a stretching treatment. Amethod and conditions of the stretching treatment, for example, is ableto refer to the publication of each of JP1987-115035A (JP-S62-15035A),JP1992-152125A (JP-H04-152125A), JP1992-284211A (JP-H104-284211A),JP1992-298310A (JP-H04-298310A), JP1999-48271A (JP-H11-48271A), and thelike.

(Casting Method)

Examples of the solution casting method include a pressure die method inwhich a prepared dope is homogeneously extruded onto a metal supportbody from a pressure die, a doctor blade method in which the filmthickness of a dope which has been casted on a metal support body isadjusted first by using a blade, a reverse roll coater method in whichthe film thickness is adjusted by using a reversely rotating roll, andthe like, and the pressure die method is preferable. A coat hanger typedie, a T die type die, or the like is used as the pressure die, and allof the dies are able to be preferably used. In addition, the solution isable to be casted by using various methods which have been known fromthe related art in which a cellulose acylate solution is casted and afilm is formed in addition to the methods described herein, and eachcondition is set in consideration of a difference in a boiling point ofa solvent to be used, or the like, and thus casting film formation isable to be performed as with a method of the related art.

Cocasting

In the formation of the cellulose acylate film, a lamination castingmethod such as a cocasting method, a sequentially casting method, and acoating method is preferably used, and a cocasting method isparticularly preferably used from a viewpoint of stable manufacturingand a reduction in production costs.

When the cellulose acylate film is manufactured by using the cocastingmethod and the sequentially casting method, first, the cellulose acetatesolution (the dope) for each layer is prepared. The cocasting method(multi-layer concurrently casting) is a casting method in which the dopeis extruded from a die for casting concurrently extruding each dope forcasting of each of the layers (three layers or three or more layers maybe used) from a separate slit or the like onto a support body forcasting (a band or a drum), the respective layers are concurrentlycasted, are peeled off from the support body at a suitable timing, andare dried, and thus a film is molded.

The sequentially casting method is a casting method in which, first, adope for casting of a first layer is extruded from the die for castingonto the support body for casting, is casted, and is dried or is notdried, and a dope for casting of a second layer is extruded from the diefor casting and is casted thereonto, and as necessary, dopes for thirdor more layers are sequentially casted and laminated, and are peeled offfrom the support body at a suitable timing and are dried, and thus acellulose acylate film is molded. In general, the coating method is amethod in which a core layer is molded into the shape of a film by usinga solution casting method, a coating liquid applied onto a surface layeris prepared, the coating liquid is applied onto each one surface or isconcurrently applied onto both surfaces of the core layer and is driedby using a suitable coating machine, and thus a cellulose acylate filmhaving a laminated structure is molded.

A drum of which the surface is subjected to mirror finishing by chromiumplating or a stainless steel belt (may be a band) which is subjected tomirror finishing by surface grinding is used as a metal support bodyendlessly traveling which is used for manufacturing the celluloseacylate film. One or two or more pressure dies to be used may bedisposed in the upper portion of the metal support body. The number ofpressure dies is preferably 1 or 2. When two or more pressure dies aredisposed, a doping amount to be casted may be divided into each of thedies at various ratios, or a dope may be fed into each of the dies froma plurality of precise quantitative gear pumps at each of the ratios.The temperature of the dope (a resin solution) used in the casting ispreferably −10° C. to 55° C., and is more preferably 25° C. to 50° C. Inthis case, the solution temperature may be identical in all of steps, ormay be different in each of the steps. When the solution temperature isdifferent in each of the steps, a desired temperature may be setimmediately before the casting.

In addition, the material of the metal support body described above isnot particularly limited, and SUS (for example, SU316) is morepreferable.

(Peeling)

It is preferable that the manufacturing method of the cellulose acylatefilm includes a step in which a film formed of the dope described aboveis peeled from the metal support body. A peeling method in themanufacturing method of the cellulose acylate film is not particularlylimited, and when a known method is used, it is possible to enhancepeelability.

(Stretching Treatment)

It is preferable that the manufacturing method of the cellulose acylatefilm includes a step in which the film is stretched after being formed.It is preferable that a stretching direction of the cellulose acylatefilm is either a cellulose acylate film transport direction (an MDdirection) or a direction orthogonal to the transport direction (a TDdirection). Furthermore, it is particularly preferable that thecellulose acylate film is stretched in the direction orthogonal to thecellulose acylate film transport direction (the TD direction) from aviewpoint of a machining process of a polarizing plate using thecellulose acylate film, which follows after the stretching.

A method of stretching the film in the TD direction, for example, isdisclosed in each of JP1987-115035A (JP-S62-115035A), JP1992-152125A(JP-H04-152125A), JP1992-284211A (JP-H04-284211A), JP1992-298310A(JP-H04-298310A), JP1999-48271A (JP-H11-48271A), and the like. When thefilm is stretched in the MD direction, for example, the speed of atransport roller of the cellulose acylate film is adjusted, and thewinding speed of the cellulose acylate film is faster than the peelingspeed of the cellulose acylate film, and thus the cellulose acylate filmis stretched. When the film is stretched in the TD direction, thecellulose acylate film is able to be stretched also by transporting thecellulose acylate film while holding the width of the cellulose acylatefilm with a tenter, and by gradually widening the width of the tenter.It is also possible to stretch the cellulose acylate film by using astretching machine (preferably monoaxial stretching using a longstretching machine) after drying the cellulose acylate film.

When the cellulose acylate film is used as a protective film of apolarizer, a light leakage is suppressed when a polarizing plate isobliquely viewed, and thus it is necessary that a transmission axis ofthe polarizer and an in-plane slow axis of the cellulose acylate filmare arranged to be parallel to each other. In general, a transmissionaxis of a roll film-like polarizer which is continuously manufactured isparallel to a width direction of the roll film, and thus in order tocontinuously bond the protective film which is formed of the rollfilm-like polarizer described above and a roll film-like celluloseacylate film, it is necessary that an in-plane slow axis of the rollfilm-like protective film is parallel to a width direction of thecellulose acylate film. Accordingly, it is preferable that furtherstretching is performed in the TD direction. In addition, the stretchingtreatment may be performed during a film forming step, or a raw fabricwhich is formed and is wound may be subjected to the stretchingtreatment.

The stretching in the TD direction is preferably stretching of 5% to100%, is more preferably stretching of 5% to 80%, and is particularlypreferably stretching of 5% to 40%. Furthermore, unstretching indicatesthat the stretching is 0%. The stretching treatment may be performedduring the film forming step, or a raw fabric which is formed and iswound may be subjected to the stretching treatment. In the former case,the stretching may be performed in a state of including a residualsolvent, and the stretching is able to be preferably performed whenAmount of Residual Solvent=(Residual Volatile Component Mass/Film Massafter Heating Treatment)×100% is 0.05% to 50%. It is particularlypreferable that stretching of 5% to 80% is performed in a state wherethe amount of residual solvent is 0.05% to 5%.

(Drying)

It is preferable that a step of drying the cellulose acylate film and astep of stretching the cellulose acylate film after being dried at atemperature of higher than or equal to a glass transition temperature(Tg)−10° C. are included in the manufacturing method of the celluloseacylate film from a viewpoint of retardation expression properties.

In the manufacturing of the cellulose acylate film, the dope on themetal support body is dried, in general, by using a method of applyinghot air from the surface side of the metal support body (the drum or thebelt), that is, from the surface of the web on the metal support body, amethod of applying hot air from the back surface of the drum or thebelt, a back surface liquid heat transmitting method in which atemperature controlled liquid is in contact with the back surface of thebelt or the drum on a side opposite to the surface on which the dope iscasted, the drum or the belt is heated by heat transmission, and thesurface temperature is controlled, and the like, and among them, theback surface liquid heat transmitting method is preferable. The surfacetemperature of the metal support body before being casted is not limitedinsofar as the surface temperature of the metal support body beforebeing casted is lower than or equal to the boiling point of the solventwhich is used in the dope. However, in order to accelerate the dryingand in order to eliminate fluidity on the metal support body it ispreferable that the surface temperature of the metal support body beforebeing casted in the solvent to be used is set to a temperature 1° C. to10° C. lower than the boiling point of the solvent having the lowestboiling point. Furthermore, when the casted dope is peeled off withoutbeing cooled and dried, the surface temperature of the metal supportbody before being casted is not limited thereto.

The thickness of the cellulose acylate film may be adjusted to have adesired thickness by adjusting the concentration of solid contentscontained in the dope, a slit gap of a base in the die, an extrusionpressure from the die, the speed of the metal support body, and thelike.

The length of the cellulose acylate film obtained as described above ispreferably wound in 100 m to 10000 m per one roll, is more preferablywound in 500 m to 7000 m, and is even more preferably wound in 1000 m to6000 m. At the time of winding the cellulose acylate film, it ispreferable that a knurling is applied to at least one end, the width ofthe knurling is preferably 3 mm to 50 mm, and is more preferably 5 mm to30 mm, and the height of the knurling is preferably 0.5 μm to 500 μm,and is more preferably 1 μm to 200 μm. The cellulose acylate film may bepressed at one side, or may be pressed at both sides.

When the optical film of the present invention is used as an opticalcompensation film for a large-screen liquid crystal display device, forexample, it is preferable that the film is molded such that the widththereof is greater than or equal to 1470 mm. In addition, when theoptical film of the present invention is used as a polarizing plateprotective film, not only an optical film having an aspect of a filmpiece which is cut to have a size capable of being directly incorporatedin a liquid crystal display device, but also an optical film having anaspect in which the film is prepared in the shape of a long film bycontinuous production, and is wound into the shape of a roll areincluded. The optical film having the latter aspect is kept andtransported in this state, and is used by being cut to have a desiredsize when the optical film is practically incorporated in the liquidcrystal display device or when the optical film is bonded to thepolarizer or the like. In addition, when the optical film is bonded to apolarizer formed of a polyvinyl alcohol film which is similarly preparedin the shape of a long film in a long shape, and then is practicallyincorporated in the liquid crystal display device, the optical film isused by being cut to have a desired size. One aspect of the opticalcompensation film or the polarizing plate protective film which is woundin the shape of a roll includes an aspect in which the film is wound inthe shape of a roll having a roll length of greater than or equal to2500 m.

<<Hard Coat Layer>>

In the optical film of the present invention, the hard coat layer whichis disposed on the cellulose acylate film as necessary is a layer forapplying hardness or scratch resistance to the optical film of thepresent invention.

For example, a coating composition for forming the hard coat layer isapplied onto the cellulose acylate film and is cured, and thus the hardcoat layer having high adhesiveness with respect to the celluloseacylate film with the compound denoted by General Formula (A) in thepresent invention is able to be formed. A filler or an additive is addedinto the hard coat layer, and thus mechanical performance, electricalperformance, optical performance, physical performance, or chemicalperformance such as water repellency and oil repellency is able to beapplied to the hard coat layer itself. The thickness of the hard coatlayer is preferably 0.1 μm to 6 μm, and is more preferably 3 μm to 6 μm.By including a thin hard coat layer having a thickness in such a range,an optical film including the hard coat layer is obtained in whichphysical properties such as suppression of brittleness or curling areenhanced, and a reduction in weight and manufacturing costs arerealized.

It is preferable that the hard coat layer is formed by curing a curablecomposition for forming the hard coat layer. It is preferable that thecurable composition is prepared as a liquid-like coating composition. Anexample of such a coating composition contains a monomer or an oligomerfor a matrix forming binder, polymers, and an organic solvent. Thiscoating composition is cured after being applied, and thus the hard coatlayer is able to be formed. In the curing, a cross-linking reaction or apolymerization reaction is able to be used.

(Monomer or Oligomer for Matrix Forming Binder)

Examples of the monomer or the oligomer for a matrix forming binderwhich is able to be used include an ionizing radiation curablemultifunctional monomer and an ionizing radiation curablemultifunctional oligomer. It is preferable that the multifunctionalmonomer or the multifunctional oligomer is a monomer which is able to besubjected to a cross-linking reaction or a polymerization reaction. Aphotopolymerizable functional group, an electron beam polymerizablefunctional group, and a radiation polymerizable functional group arepreferable as the functional group of the ionizing radiation curablemultifunctional monomer or the ionizing radiation curablemultifunctional oligomer, and among them, the photopolymerizablefunctional group is preferable.

Examples of the photopolymerizable functional group include anunsaturated polymerizable functional group such as a (meth)acryloylgroup, a vinyl group, a styryl group, and an allyl group, and a ringopening polymerization type polymerizable functional group such as anepoxy-based compound, and among them, the (meth)acryloyl group ispreferable.

Specific examples of the photopolymerizable multifunctional monomerhaving a photopolymerizable functional group include (meth)acrylicdiesters of alkylene glycol such as neopentyl glycol di(meth)acrylate,1,6-hexane diol di(meth)acrylate, and propylene glycol di(meth)acrylate;(meth)acrylic diesters of polyoxy alkylene glycol such as triethyleneglycol di(meth)acrylate, dipropylene glycol di(meth)acrylate,polyethylene glycol di(meth)acrylate, and polypropylene glycoldi(meth)acrylate; (meth)acrylic diesters of polyvalent alcohol such aspentaerythritol di(meth)acrylate; (meth)acrylic diesters of an adduct ofethylene oxide or propylene oxide such as2,2-bis{4-(acryloxy.diethoxy)phenyl}propane, and2,2-bis{4-(acryloxy.polypropoxy)phenyl}propane; and the like.

Further, urethane (meth)acrylates, polyester (meth)acrylates,isocyanuric acid (meth)acrylates, and epoxy (meth)acrylates are alsopreferably used as the photopolymerizable multifunctional monomer.

Among them, esters of polyvalent alcohol and (meth)acrylate arepreferable, and a multifunctional monomer having three or more(meth)acryloyl groups in one molecule is more preferable.

Specifically, (di)pentaerythritol tri(meth)acrylate, (di)pentaerythritoltetra(meth)acrylate, (di)pentaerythritol penta(meth)acrylate,(di)pentaerythritol hexa(meth)acrylate, tripentaerythritoltri(meth)acrylate, tripentacrythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylol ethane tri(meth)acrylate,ditrimethylol propane tetra(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylol propanetri(meth)acrylate, EO-modified phosphoric acid tri(meth)acrylate,1,2,4-cyclohexane tetra(meth)acrylate, pentaglycerol tri(meth)acrylate,1,2,3-cyclohexane tetra(meth)acrylate, polyester polyacrylate,caprolactone-modified tris((meth)acryloxy ethyl) isocyanurate, and thelike are included.

Herein, “(meth)acrylate”, “(meth)acrylic acid”, and “(meth)acryloyl”respectively indicate “acrylate or methacrylate”, “acrylic acid ormethacrylic acid”, and “acryloyl or methacryloyl”.

Further, examples of a resin having three or more (meth)acryloyl groupsinclude a polyester resin, a polyether resin, an acrylic resin, an epoxyresin, a urethane resin, an alkyd resin, a spiroacetal resin, apolybutadiene resin, and a polythiol polyene resin which have acomparatively low molecular weight, an oligomer or a prepolymer of amultifunctional compound or the like such as polyvalent alcohol, and thelike.

A specific compound of the multifunctional acrylate-based compoundshaving three or more (meth)acryloyl groups is able to refer to compoundsdisclosed in paragraph 0096 of JP2007-256844A and the like.

Examples of the urethane (meth)acrylates are able to include a urethane(meth)acrylate-based compound which is obtained by allowing hydroxygroup-containing compounds such as alcohol, polyol, and/or a hydroxygroup-containing (meth)acrylate to react with isocyanates, or asnecessary, by esterifying a polyurethane compound obtained by thisreaction with (meth)acrylate.

A specific example of the specific compound is able to refer to examplesdisclosed in paragraph 0017 of JP2007-256844A and the like.

It is preferable that the isocyanuric acid (meth)acrylates are used froma viewpoint of capable of reducing the curling. Examples of suchisocyanuric acid (meth)acrylates include isocyanuric acid diacrylatesand isocyanuric acid triacrylates, and an example of a specific compoundis able to refer to examples disclosed in paragraphs 0018 to 0021 ofJP2007-256844A and the like.

An epoxy-based compound is able to be used in the hard coat layer inorder to further reduce contraction due to the curing. A monomer havingtwo or more epoxy groups in one molecule is used as such an epoxy-basedcompound (monomers having an epoxy group), and examples of the monomerhaving two or more epoxy groups in one molecule include epoxy-basedmonomers disclosed in each of JP2004-264563A, JP2004-264564A,JP2005-37737A, JP2005-37738A, JP2005-140862A, JP2005-140863A,JP2002-322430A, and the like. In addition, a compound having bothfunctional groups of an epoxy-based functional group and an acrylicfunctional group, such as glycidyl (meth)acrylate, is also preferablyused.

(High Molecular Compound)

The hard coat layer may contain a high molecular compound. By adding thehigh molecular compound, it is possible to decrease curing contraction,it is possible to more preferentially adjust viscosity of the coatingliquid relevant to dispersion stability of resin particles (aggregationproperties), and it is possible to change aggregation behavior of theresin particles by controlling the polarity of a solidified materialduring the drying or to reduce drying unevenness during the drying, andthus adding the high molecular compound is preferable.

Here, the high molecular compound is a compound which forms a polymer inadvance at the time of being added into the coating liquid. Resins suchas cellulose esters (for example, cellulose triacetate, cellulosediacetate, cellulose propionate, cellulose acetate propionate, celluloseacetate butyrate, cellulose nitrate, and the like), urethanes,polyesters, (meth)acrylic esters (for example, a methylmethacrylate/methyl (meth)acrylate copolymer, a methylmethacrylate/ethyl (meth)acrylate copolymer, a methyl methacrylate/butyl(meth)acrylate copolymer, a methyl methacrylate/styrene copolymer, amethyl methacrylate/(meth)acrylate copolymer, polymethyl methacrylate,and the like), and polystyrene are preferably used as such a highmolecular compound.

(Curable Composition)

An example of a curable composition which is able to be used for formingthe hard coat layer is a curable composition including a(meth)acrylate-based compound. It is preferable that the curablecomposition contains a photoradical polymerization initiator or athermal radical polymerization initiator along with the(meth)acrylate-based compound, and as necessary, may further contain afiller, a coating auxiliary agent, and other additives. The curablecomposition is able to be cured by performing a polymerization reactiondue to irradiation or heating of ionizing radiation in the presence ofthe photoradical polymerization initiator or the thermal radicalpolymerization initiator. In addition, both of ionizing radiation curingand thermal curing are able to be performed. A commercially availablecompound is able to be used as an optical polymerization initiatorand/or a thermal polymerization initiator. The optical polymerizationinitiator and/or the thermal polymerization initiator is disclosed in“Newest UV Curing Technology” (p. 159, Publisher; Kazuhiro TAKAUSU,Publishing Office; published by Technical Information Institute Co.,Ltd., in 1991) or in a catalog of BASF SE.

Another example of the curable composition which is able to be used forforming the hard coat layer is a curable composition containing anepoxy-based compound. It is preferable that the curable compositioncontains a photoacid generator generating cations due to the action oflight along with the epoxy-based compound, and as necessary, may furthercontain a filler, a coating auxiliary agent, and other additives. Thecurable composition is able to be cured by performing a polymerizationreaction due to light irradiation in the presence of the photoacidgenerator. Examples of the photoacid generator include an ionic compoundsuch as a triaryl sulfonium salt and a diaryl iodonium salt, a nonioniccompound such as nitrobenzyl ester of a sulfonic acid, and the like. Inaddition, various arbitrary photoacid generators such as compoundsdisclosed in The Japanese Research Association for Organic ElectronicsMaterials, “Organic Material for Imaging”, published by Bunshin DesignPrinting Publishing And Digital Communications (1997), and the like areable to be used.

In addition, the (meth)acrylate-based compound and the epoxy-basedcompound may be used together, and in this case, it is preferable thatan initiator such as a photoradical polymerization initiator or athermal radical polymerization initiator, and a photocationicpolymerization initiator are used together.

The curable composition which is particularly preferable for forming thehard coat layer is a composition containing a (meth)acrylate-basedcompound to be used in examples described below.

It is preferable that the curable composition is prepared as a coatingliquid. The coating liquid is able to be prepared by dissolving and/ordispersing the components described above in an organic solvent.

(Properties of Hard Coat Layer)

The hard coat layer formed on the cellulose acylate film of the opticalfilm of the present invention has high adhesiveness with respect to thecellulose acylate film. In particular, in the hard coat layer formed ofthe preferred curable composition described above on the celluloseacylate film containing the compound denoted by General Formula (A) inthe present invention, the curable composition is formed with higheradhesiveness with respect to the cellulose acylate film along with thecompound denoted by General Formula (A). The optical film of the presentinvention including such a cellulose acylate film and a hard coat layermaintains adhesiveness between the cellulose acylate film and the hardcoat layer even when light irradiation or the like is performed, and hasexcellent optical durability.

It is preferable that the hard coat layer has excellent scratchresistance. Specifically, when a pencil hardness test (JIS-K5400) whichis an index of scratch resistance is performed, it is preferable thathardness of greater than or equal to 3 H is attained.

[Polarizing Plate]

A polarizing plate of the present invention includes a polarizer and theoptical film of the present invention on at least one surface of thepolarizer. It is preferable that the polarizing plate of the presentinvention includes the polarizer, and the optical film of the presentinvention on one surface or both surfaces of the polarizer. Thepolarizer is an iodine-based polarizer, a dye-based polarizer using adichromatic dye, or a polyene-based polarizer. The iodine-basedpolarizer and the dye-based polarizer are generally manufactured byusing a polyvinyl alcohol-based film. When the optical film of thepresent invention is used as a polarizing plate protective film, apreparing method of the polarizing plate is not particularly limited,and the polarizing plate is able to be prepared by using a generalmethod. For example, the general method is a method in which thecellulose acylate film of the optical film of the present invention issubjected to an alkali treatment and the cellulose acylate film isbonded to both surfaces of the polarizer prepared by dipping andstretching a polyvinyl alcohol film in an iodine solution by using anaqueous solution of fully saponified polyvinyl alcohol. Instead of thealkali treatment, easy adhesion processing as disclosed in JP1994-94915A(JP-H06-94915A) and JP1994-118232A (JP-H06-118232A) may be performed.Examples of an adhesive agent used for bonding a treatment surface ofthe cellulose acylate film to the polarizer include a polyvinylalcohol-based adhesive agent such as polyvinyl alcohol and polyvinylbutyral, vinyl-based latex such as butyl acrylate, and the like.

It is preferable that the optical film of present invention is bonded tothe polarizer such that a transmission axis of the polarizer and a slowaxis of the optical film of the present invention are substantiallyorthogonal to each other, parallel to each other, or at an angle of 45°.In a liquid crystal display device of the present invention, it ispreferable that the transmission axis of the polarizer and the slow axisof the optical film of the present invention are substantiallyorthogonal to each other. Here, the expression “substantially parallelor orthogonal” includes a range of an error which is allowable in theart to which the present invention belongs. For example, the expression“substantially parallel or orthogonal” indicates a range of less than±10° from an exact angle relevant to parallel and orthogonal, and anerror from the exact angle is preferably less than or equal to 5°, andis more preferably less than or equal to 3°.

The transmission axis of the polarizer and the slow axis of thepolarizing plate protective film being parallel to each other indicatesthat an angle between the direction of the main refractive index nx ofthe polarizing plate protective film and the direction of thetransmission axis of the polarizer is in a range of ±10°. The range ofsuch an angle is preferably ±5, is more preferably ±3, is even morepreferably ±1, and is particularly preferably ±0.5°. Furthermore, whenthe angle is 0°, the direction of the main refractive index nx of thepolarizing plate protective film and the direction of the transmissionaxis of the polarizer are completely parallel to each other withoutintersecting with each other.

In addition, the transmission axis of the polarizer and the slow axis ofthe polarizing plate protective film being orthogonal to each otherindicates that the direction of the main refractive index nx of thepolarizing plate protective film and the direction of the transmissionaxis of the polarizer intersect with each other at an angle of 90°±10°.The angle is preferably 90°±5°, is more preferably 90°±3°, is even morepreferably 90°±1°, and is particularly preferably 90°±0.5°.

By setting the range described above, a light leakage is able to befurther reduced under a polarizing plate crossed-Nicols. The slow axisis able to be measured by various arbitrary methods, and for example, isable to be measured by using a birefringence meter (KOBRA DH,manufactured by Oji Scientific Instruments).

The polarizing plate of the present invention includes not only apolarizing plate having a shape of a film piece which is cut to have asize capable of being directly incorporated in the liquid crystaldisplay device, but also a polarizing plate having a shape in which afilm is prepared in the shape of a long film due to continuousproduction, and is wound into the shape of a roll (for example, a shapein which a roll length is greater than or equal to 2500 m or greaterthan or equal to 3900 m). In order to use the polarizing plate of thepresent invention for a large-screen liquid crystal display device, itis preferable that the width of the polarizing plate is greater than orequal to 1470 mm. A specific configuration of the polarizing plate ofthe present invention is not particularly limited, and is able to adoptan arbitrary configuration. For example, a configuration disclosed inFIG. 6 of JP2008-262161A is able to be adopted.

[Liquid Crystal Display Device]

The liquid crystal display device of the present invention includes atleast a liquid crystal cell, and the polarizing plate of the presentinvention. A liquid crystal display device in a mode of IPS, OCB, or VAin which a polarizing plate is the polarizing plate of the presentinvention is preferable as the liquid crystal display device of thepresent invention. In addition, when a first polarizing plate and asecond polarizing plate are included, a liquid crystal display device ina mode of IPS, OCB, or VA in which at least one polarizing plate is thepolarizing plate of the present invention is preferable as the liquidcrystal display device of the present invention.

It is preferable that the liquid crystal display device of the presentinvention includes a liquid crystal cell (a liquid crystal layer), andpolarizing plates which are laminated on both sides of the liquidcrystal cell and are provided with an optical films on a surface on aside opposite to the liquid crystal cell side. That is, it is preferablethat the liquid crystal display device of the present invention includesthe first polarizing plate, the liquid crystal cell, and the secondpolarizing plate, and includes the optical film of the present inventionon a surface on a side opposite to the polarizing plate surface sideinterposed between each of the polarizing plates and the liquid crystalcell. In the liquid crystal display device having such a configuration,display unevenness is excellently suppressed, and high displayperformance is exhibited.

In addition, it is preferable that the liquid crystal display device ofthe present invention includes the optical film in which the polarizingplate arranged on a visible side includes the hard coat layer on thesurface of the optical film on the visible side, and in particular,includes the cellulose acylate film. In the liquid crystal displaydevice having such a configuration, excellent scratch resistance andexcellent optical durability are exhibited in addition to high displayperformance which is excellent for suppressing display unevenness.

An inner configuration of a typical liquid crystal display device whichis the liquid crystal display device of the present invention areillustrated in FIG. 1 and FIG. 2. In FIG. 1, a liquid crystal displaydevice is illustrated in which optical films 31 a and 31 b of thepresent invention which are formed of the cellulose acylate film includepolarizing plates 21A and 21B arranged on both surfaces of a polarizer32. In addition, in FIG. 2, a liquid crystal display device providedwith an optical film 31 a′ in which the polarizing plate 21B arranged onthe visible side includes a hard coat layer 311 b on the surface of thepolarizer 32 on the visible side through a cellulose acylate film 311 ais illustrated.

Furthermore, FIG. 1 and FIG. 2 illustrate a configuration of an exampleof the liquid crystal display device of the present invention, and aspecific configuration of the liquid crystal display device of thepresent invention is not particularly limited, but a known configurationis able to be adopted. In addition, a configuration disclosed in FIG. 2of JP2008-262161A is also able to be preferably adopted.

EXAMPLES

Hereinafter, the present invention will be described in more detail withreference to examples, but the present invention is not limitedlyinterpreted by the examples.

[Synthesis of Compound Denoted by General Formula (A)]

The compound denoted by General Formula (A) in the present invention wassynthesized as follows.

Representative synthesis examples of the compound are shown as follows.

Furthermore, the structure of the obtained compound was confirmed byusing a ¹H-NMR spectrum and a mass spectrum.

Synthesis Example 1

An exemplary compound (2-7) was synthesized by using the followingreaction scheme.

1) Synthesis of Intermediate (S-2)

25 g (0.16 mol) of an N,N′-dimethyl barbituric acid (S-1), 10.7 g (0.08mol) of isophthalaldehyde, and 400 mL of an acetic acid were added to athree neck flask of 1000 mL which was attached with a thermometer, acirculation cooling tube, and a stirrer, and 2 mL of a sulfuric acid wasfurther added thereto, and then the mixture was heated and stirred at anexternal temperature of 150° C. for 3 hours. After that, 300 mL of anacetic acid was distilled under reduced pressure. The obtained reactionsolution was cooled to room temperature, 500 mL of methanol was added tothe reaction solution, and then the mixture was distilled at atemperature of lower than or equal to 10° C. for 1 hour, an educedcrystal was subjected to suction filtration, and was washed withmethanol, and thus 31 g (a yield of 94%) of an intermediate (S-2) wasobtained as a pale-yellow solid.

2) Synthesis of Exemplary Compound (2-7)

20.5 g (0.050 mol) of the intermediate (S-2) and 500 mL of an aceticacid were added to a three neck flask of 1000 mL which was attached witha thermometer, a circulation cooling tube, and a stirrer, and themixture was heated and stirred at 120° C. 49 g (0.75 mol) of a zincpowder was gradually added thereto in a small amount while being carefulof heat generation and foaming. In this state, the mixture wascontinuously heated and circulated for 3 hours, and then 400 mL of anacetic acid was distilled under reduced pressure. The obtained reactionsolution was cooled to room temperature, and then was separated intoethyl acetate and a saline solution, and thus an object substance wasextracted into an organic layer. Further, the obtained organic layer waswashed with a saline solution, and then was dried with magnesiumsulfate, and thus a solvent was vacuum-distilled. The obtained crudebody was purified by using silica gel column chromatography (ethylacetate/hexane), and thus an exemplary compound (2-7) was obtained as awhite solid (8 g, a yield of 39%).

The structure of the obtained compound was confirmed by using a ¹H-NMRspectrum and a mass spectrum.

¹H-NMR (300 MHz, DMSO-d₆), δ: 7.20 (t, 1H), 6.89 (d, 2H), 6.74 (s, 1H),4.00 (s, 2H), 3.20 (d, 4H), 3.01 (s, 12H)

Mass Spectrum: m/z 415 (M+H)⁺

Synthesis Example 2

An exemplary compound (2-6) was synthesized through the followingintermediate (S-3).

1) Synthesis of Intermediate (S-3)

A corresponding intermediate (S-3) was obtained by the same method asthat in Synthesis of Intermediate (S-2) of the exemplary compound (2-7)using an N,N′-dimethyl barbituric acid and terephthalaldehyde.

2) Synthesis of Exemplary Compound (2-6)

14.4 g (0.035 mol) of the intermediate (S-3) and 500 mL of an aceticacid were added to a three neck flask of 1000 mL which was attached witha thermometer, a circulation cooling tube, and a stirrer, and then themixture was heated and stirred at 120° C. 34.3 g (0.53 mol) of a zincpowder was gradually added thereto in a small amount while being carefulof heat generation and foaming. In this state, the mixture wascontinuously heated and circulated for 3 hours, and then a reactionsolution was subjected to hot filtration. 400 mL of an acetic acid wasdistilled from the objected filtrate under reduced pressure. Methanolwas added to the obtained residue and recrystallization was performed,and thus an exemplary compound (2-6) was obtained as a white solid (10g, a yield of 69%).

The structure of the obtained compound was confirmed by using a massspectrum.

Mass Spectrum: m/z 415 (M+H)⁺

Synthesis Example 3

An exemplary compound (1-6) was synthesized by using the followingreaction scheme.

1) Synthesis of Intermediate (S-4)

18.6 of aniline and 200 mL of THE were added to a three neck flask of500 mL and were stirred under ice cooling, and then 18.8 g of xylylenediisocyanate was gradually added thereto. After dripping, a reactionsolution of which the temperature returned to room temperature wasstirred for 2 hours, 200 mL of hexane was added thereto, and a crystal(S-4) was filtered. This intermediate (S-4) was not purified any more,and was used in the next step.

2) Synthesis of Exemplary Compound (1-6)

An exemplary compound (1-6) was synthesized by using the intermediate(S-4) and diethyl malonate.

18.7 g of the intermediate (S-4), 17.6 g of diethyl malonate, and 102.1g (030 mol) of a sodium ethoxide/ethanol solution of 20% were put into athree neck flask of 300 mL which was attached with a thermometer, acirculation cooling tube, and a stirrer, and the mixture was stirred for4 hours under heating circulation. After that, a part of ethanol wasdistilled, the mixture was cooled to room temperature, and 100 mL ofethyl acetate was added thereto. The educed solid was subjected tosuction filtration, and was washed with ethyl acetate. This solid (asodium salt) was dissolved in 100 mL of water, a hydrochloric acid wasdripped such that pH was 1, and thus eduction was performed. The educedsolid was subjected to suction filtration, and was washed with water.Further, this crude body was purified by recrystallization, and thus12.8 g of an exemplary compound (1-6) was obtained as a white solid.

The structure of the obtained compound was confirmed by using a massspectrum.

Mass Spectrum: m/z 511 (M+H)⁺

Synthesis Example 4

An exemplary compound (1-7) was synthesized through the intermediate(S-4).

An exemplary compound (1-7) was synthesized by the same method as thatin Synthesis of Exemplary Compound (1-6) using the intermediate (S-4)and benzyl diethyl malonate except that diethyl malonate was changed tobenzyl diethyl malonate.

The structure of the obtained compound was confirmed by using a massspectrum.

Mass Spectrum: m/z 692 (M+H)⁺

Synthesis Example 5

A mixture of exemplary compounds (2-7), (3-1), and (3-14) wassynthesized by the same method as that in Synthesis Example 1 exceptthat an N,N′-dimethyl barbituric acid and N-benzyl-N′-phenyl barbituricacid were used by being equivalently mixed instead of the N,N′-dimethylbarbituric acid (S-1) in Synthesis Example 1. This mixture was used inthis state without isolating each of the exemplary compounds.

Compound other than the compounds used in the examples were synthesizedby a method similar to that described above, a method disclosed in theliterature described above, or a method based thereon.

Example 1

As described below, a cellulose acylate film (an optical film) wasprepared, and film hardness, haze, and durability of film coloration dueto light (aging coloration) were evaluated.

<Optical Film: Film Formation of Single-Layered Cellulose Acylate Film>

(Preparation of Cellulose Acylate Solution)

The following compositions were put into a mixing tank, each componentwas dissolved by being stirred, and thus a cellulose acylate solutionwas prepared.

Composition of Cellulose Acylate Solution Cellulose Acylate HavingDegree of Acetyl 100.0 parts by mass Substitution of 2.87 and Degree ofPolymerization of 370 Additive Shown in Table 1 Described below 10.0parts by mass Methylene Chloride (First Solvent) 353.9 parts by massMethanol (Second Solvent) 89.6 parts by mass n-Butanol (Third Solvent)4.5 parts by mass

Each of the cellulose acylate solutions prepared as described above wascasted by using a drum casting device. Peeling off was performed in astate where the amount of residual solvent in a dope was approximately70 mass %, and drying was performed in a state where the amount ofresidual solvent was 3 mass % to 5 mass %. After that, the drying wasfurther performed by transporting the casted solution between rolls of aheat treatment device, and thus optical films Nos. 101 to 105 having afilm thickness of 60 μm were obtained.

Here, these optical films were referred to as a polarizing plateprotective film, hereinafter.

In addition, the compound denoted by General Formula (A) was referred toas an additive, hereinafter.

[Evaluation of Film Hardness of Optical Film]

Film hardness was evaluated on the basis of a method of JIS Z 2251 by aknoop indenter in which the direction of a short axis of the indenterwas arranged to be parallel to a transport direction (a longitudinaldirection; a test direction in a pencil hardness test) at the time offorming the optical film using a “Fischer Scope H100Vp type hardnessmeter” manufactured by Fischer Instruments K. K. Specifically, a samplesurface fixed to a glass substrate was measured in conditions of aloading time of 10 seconds, a creeping time of 5 seconds, an offloadingtime of 10 seconds, and a maximum load of 50 mN, and the hardness wascalculated from a relationship between a contact area of the indenterand the sample and the maximum load which was obtained from anindentation depth, and the average value of five points was set tosurface hardness of the knoop hardness. Furthermore, JIS Z 2251 wasJapanese Industrial Standards prepared on the basis of ISO4545.

Furthermore, in the same indentation position, the knoop indenter wasrotated by each 10°, knoop hardness was measured at 18 directions (alldirections) in total, and thus the minimum value was obtained. Theminimum value was coincident with the surface hardness which wasmeasured by arranging the direction of the short axis of the knoopindenter described above to be parallel to the transport direction (thelongitudinal direction; the test direction in the pencil hardness test)at the time of forming the optical film.

The obtained surface hardness was evaluated according to the followingcriteria as the film hardness.

The results were shown in Table 1 described below.

A+: The knoop hardness of greater than or equal to 225 N/mm²

A: The knoop hardness of greater than or equal to 215 N/mm² and lessthan 225 N/mm²

B: The knoop hardness of greater than or equal to 205 N/mm² and lessthan 215 N/mm²

C: The knoop hardness of greater than or equal to 190 N/mm² and lessthan 205 N/mm²

D: The knoop hardness of less than 190 N/mm²

[Haze Evaluation]

The haze of each of the optical films obtained as described above wasmeasured and was evaluated on the following criteria of A to C, and theresults were shown in Table 1 described below.

The haze was measured by measuring each of the optical films using ahazemeter “HGM-2DP” (a product name, manufactured by Suga TestInstruments Co., Ltd.) according to JIS K-7136.

A: The haze of less than 0.3%

B: The haze of greater than or equal to 0.3% and less than 0.7%

C: The haze of greater than or equal to 0.7%

[Evaluation of Durability of Film Coloration Due to Light (AgingColoration)]

Light irradiation was performed with respect to each of the opticalfilms prepared as described above for 120 hours in conditions ofirradiance of 150 W/m², a black panel temperature of 63° C. and relativehumidity of 50% by using a super xenon weather meter (a product name:SX75, manufactured by Suga test Instruments Co., Ltd.,). After that, hueb* was measured by using a spectrophotometer UV3150 manufactured byShimadzu Corporation. When the value of the hue b* is increased on aminus side, a bluishe color of transmitted light is increased, and whenthe value of the hue b* is increased on a plus side, a yellowish colorof the transmitted light is increased.

In addition, the absolute value of a change in the value of b* of eachof the optical films before and after the light irradiation was set toan index of the coloration due to light as Δb* and was evaluated as A toD according to the following criteria.

A: Δb* of less than or equal to 0.05

B: Δb* of greater than 0.05 and less than or equal to 0.10

C: Δb* of greater than 0.10 and less than or equal to 0.15

D: Δb* of greater than 0.15

TABLE 1 Additive Com- Film Aging Film pound Added Added Hard- Color- No.Number Amount^(Note 1)) Amount^(Note 2)) ness ation Haze Notes 101 1-110 19.6 mmol  A+ B A Present Invention 102 1-2 10 18.6 mmol  A+ A APresent Invention 103 Comparative 5.8 19.6 mmol B C A ComparativeCompound 1 Example 104 Comparative 11.5 39.2 mmol A C A ComparativeCompound 1 Example 105 None 0 0 D A A Reference Example^(Note 1))indicates the number of grams per 100 g of cellulose acylate.^(Note 2))indicates the number of moles per 100 g of cellulose acylate.

Here, a comparative compound 1 is a compound disclosed inJP2011-118135A.

As it is obvious from Table 1 described above, the optical film of thepresent invention having the compound denoted by General Formula (A) hadhigh film hardness. It is considered that this is because the compounddenoted by General Formula (A) in the present invention easily enters agap in a molecular chain of cellulose acylate, and a hetero ringstructure portion in General Formula (I) effectively acted on an acetylgroup and a hydroxy group of the cellulose acylate, a hydrogen bond isformed, and thus the movement of the molecular chain of the celluloseacylate is suppressed. Further, it is considered that the compounddenoted by General Formula (A) in the present invention has a highpolarity and excellent compatibility with respect to the celluloseacylate, and thus efficiently acts on the cellulose acylate.

In comparison with the optical films Nos. 101 and 103, it is found thateven when the additive is added in the same number of moles, thecompound denoted by General Formula (A) in the present inventionexpresses high film hardness. It is considered that this is because twounits of hetero ring structures in General Formula (I) having a functionof improving hardness are included in one molecule.

Further, in comparison with the optical films Nos. 101 and 104, it isfound that even when the same unit amount of a partial structure denotedby General Formula (I) is included, the compound denoted by GeneralFormula (A) in the present invention expresses higher film hardness thanthe film hardness of a case where the amount of the comparative compound1 is used twice.

It is considered that this is because in the compound denoted by GeneralFormula (A) in the present invention, the units of the partial structuredenoted by General Formula (I) are densely arranged in the molecules,and the hetero ring structure in General Formula (I) easily mutuallyinteracts with β-glucose of the cellulose acylate. Accordingly, it isconsidered that high film hardness is obtained by an effect in which thehetero ring structure denoted by General Formula (I) in the samemolecules mutually interacts in the optical film such that differentcellulose acylate polymer chains are cross-linked. In addition, incomparison with the comparative compound 1, it is found that thecompound denoted by General Formula (A) in the present invention alsosuppresses the coloration due to light.

Example 2

Optical films Nos. 201 to 209 were prepared by the same method as thatin Example 1 except that the type of each of the additives was changedas shown in Table 2 described below. In addition, each of the propertiesand the physical properties was evaluated by the same method as that inExample 1.

Furthermore, the pencil hardness was evaluated by using an optical filmattached with a hard coat layer which was prepared by forming a hardcoat layer as described below onto a cellulose acylate film (an opticalfilm) of each of the films Nos. 201 to 209 described above.

<Preparation of Optical Film Attached with Hard Coat Layer>

A hard coat layer solution having the following curable composition wasapplied onto the surface of a single-layered optical film formed of eachof the cellulose acylates prepared as described above and was cured bybeing irradiated with an ultraviolet ray, and thus each optical filmattached with a hard coat layer was prepared on which a hard coat layerhaving a thickness of 6 μm was formed.

Furthermore, in Table 2 described below and the following examples, acommon film No. is applied to a single-layered optical film No. and anoptical film attached with a hard coat layer No. corresponding thereto.

Composition of Hard Coat Layer Solution Monomer PentaerythritolTriacrylate/ 53.5 parts by mass Pentaerythritol Tetraacrylate (MixedMass Ratio of 3/2) UV Polymerization Initiator IrgacureTM907 1.5 partsby mass (manufactured by BASF SE) Ethyl Acetate 45 parts by mass

[Pencil Hardness Evaluation]

The humidity of each of the optical film attached with a hard coat layerwas adjusted for 2 hours in conditions of a temperature of 25° C. andrelative humidity of 60%, and the pencil hardness was measured by usinga pencil for a test defined in JIS-S6006 according to a pencil hardnessevaluation method defined in JIS-K5400. Specifically, the surface of thehard coat layer was repeatedly scratched 5 times with a pencil with eachhardness by using a weight of 500 g, and the hardness was measured untilthe number of defects became 1.

Here, it is disclosed that a defect defined in JIS-K5400 is a breakageof a coated film and a scratch of the coated film, but concavity of thecoated film is not a target. However, in this evaluation, the concavityof the coated film was also determined as a defect.

Durability of a polarizing plate was evaluated by using the opticalfilms Nos. 201 to 209 before preparing the optical film attached with ahard coat layer as a polarizing plate protective film, by performing asaponification treatment with respect to the optical films Nos. 201 to209, and by preparing a polarizing plate as described below.

<Preparation of Polarizing Plate>

(Saponification Treatment of Polarizing Plate Protective Film)

The optical films Nos. 201 to 209 before preparing the optical filmattached with a hard coat layer were used as a polarizing plateprotective film. Each of the polarizing plate protective films wasdipped in 2.3 mol/L of an aqueous solution of sodium hydroxide at 55° C.for 3 minutes. After that, the polarizing plate protective film waswashed in a water washing bath at room temperature, and was neutralizedat 30° C. by using 0.05 mol/L of a sulfuric acid. The polarizing plateprotective film was washed again in the water washing bath at roomtemperature, and was further dried with hot air at 100° C. Thus, asaponification treatment was performed with respect to the surface ofeach of the polarizing plate protective films.

(Preparation of Polarizing Plate)

Iodine was adsorbed in a stretched polyvinyl alcohol film, and thus apolarizer was prepared.

The polarizing plate protective film which was subjected to thesaponification treatment described above was bonded to one side of thepolarizer by using a polyvinyl alcohol-based adhesive agent. Acommercially available cellulose triacetate film (Fujitac TD80UF,manufactured by Fujifilm Corporation) was also subjected to the samesaponification treatment. The commercially available cellulosetriacetate film which had been subjected to the saponification treatmentwas bonded to the surface of the polarizer on a side opposite to thesurface side onto which the polarizing plate protective film subjectedto the saponification treatment was bonded by using the polyvinylalcohol-based adhesive agent.

At this time, a transmission axis of the polarizer and a slow axis ofthe polarizing plate protective film which had been subjected to thesaponification treatment were arranged to be parallel to each other. Inaddition, the transmission axis of the polarizer and a slow axis of thecommercially available cellulose triacetate film which had beensubjected to the saponification treatment were arranged to be orthogonalto each other.

Thus, each polarizing plate corresponding to each of the optical filmsNos. 201 to 209 was prepared.

[Evaluation of Durability of Polarizing Plate]

A durability test of the polarizing plate was performed in a state wherethe polarizing plate was bonded to glass through an adhesive agent asfollows.

Two samples (approximately 5 cm×5 cm) were prepared in which thepolarizing plate was bonded onto glass such that the optical film of thepresent invention was on an air boundary side. Orthogonal transmittancemeasurement of a single plate was performed by setting a side of theoptical film of the present invention in this sample to be directedtowards a light source. Each of the two samples was measured, and theaverage value thereof was set to orthogonal transmittance of thepolarizing plate of the present invention. The orthogonal transmittanceof the polarizing plate was measured in a range of 380 nm to 780 nm byusing an automatic polarizing film measurement device VAP-7070manufactured by Jasco Corporation, and a measured value at 410 nm wasadopted. After that, the sample was aged and held for 120 hours under anenvironment of a temperature of 80° C. and relative humidity of 90%, andthe orthogonal transmittance was measured by using the same method. Achange in the orthogonal transmittance before and after aging wasobtained, and a change rate was calculated from [(Change Amount inOrthogonal Transmittance before and after Aging)/OrthogonalTransmittance before Aging] ×100. The change rate was evaluated as thedurability of the polarizing plate on the basis of the followingcriteria.

Furthermore, relative humidity under an environment where the humiditywas not adjusted was in a range of 0% to 20%.

—Evaluation Criteria—

A: The change rate in the orthogonal transmittance before and afteraging of less than 0.7%

B: The change rate in the orthogonal transmittance before and afteraging of greater than or equal to 0.7% and less than 0.8%

C: The change rate in the orthogonal transmittance before and afteraging of greater than or equal to 0.8% and less than 1.0%

D: The change rate in the orthogonal transmittance before and afteraging of greater than or equal to 1.0%

The results are collectively shown in Table 2 described below.

TABLE 2 Additive Aging Durabil- Com- Film Color- Pencil ity of Filmpound Added Hard- ation Hard- Polar- No. Number Amount ness (Light) Hazeness izing Notes 201 1-4 10 A A A 3H A Present Invention 202 1-6 10  A+A A 3H A Present Invention 203 1-7 10 A A A 3H A Present Invention 204 1-17 10  A+ A A 3H A Present Invention 205 2-2 10 A A A 3H A PresentInvention 206 2-6 10 A A A 3H A Present Invention 207 Comparative 10 A CA 3H A Comparative Compound 1 Example 208 Comparative 10 D A A 2H CComparative Compound 2 Example 209 None 0 D A A Less D Reference than 2HExample

Here, the added amount of the additive is denoted by parts by mass withrespect 100 parts by mass of the cellulose acylate.

In addition, a comparative compound 2 is a compound disclosed inJP2002-322294A.

From Table 2 described above, it was found that the optical film of thepresent invention using the compound denoted by General Formula (A) hadhigh knoop hardness (the film hardness) which was the index of thesurface hardness, small aging coloration due to light in the opticalfilm, and a low haze value. In addition, in the optical film attachedwith a hard coat layer, pencil hardness was high, and the durability ofthe polarizing plate under hygrothermal conditions was excellent.

In contrast, in the comparative compound 1, the aging coloration due tolight in the optical film was considerable, and from the comparison withthe optical film No. 209, it was found that the aging coloration wasincreased by adding the comparative compound 1. On the other hand, inthe comparative compound 2, both of the film hardness and the pencilhardness were low, and the hardness was the same degree as that of thehardness of the optical film No. 209 which was prepared without addingan additive thereto. Further, the durability of the polarizing platealso deteriorated.

Example 3

An optical film was prepared by the same method as that in Example 1except that the degree of acetyl substitution of the cellulose acylate,the type of each of the additives, and the film thickness were changedas shown in Table 3 described below.

Each of the properties and the physical properties was evaluated by thesame method as that in Example 1 and Example 2 except for the evaluationof the film hardness.

[Evaluation of Film Hardness of Optical Film]

Each of the values of the knoop hardness (the surface hardness) of theoptical film was evaluated on the basis of the following criteria bybeing compared with the value of the knoop hardness of the optical filmwhich was prepared without adding an additive thereto.

When the surface hardness was evaluated, the optical film having a filmthickness of less than or equal to 40 μm was measured by changing anindentation load from 50 mN to 20 mN.

A: Greater than or equal to 1.15 times the value of the knoop hardnessat the time of not adding the additive

B: Greater than or equal to 1.05 times and less than 1.15 times thevalue of the knoop hardness at the time of not adding the additive

C: Greater than or equal to 1.00 times and less than 1.05 times thevalue of the knoop hardness at the time of not adding the additive

D: Less than 1.00 times the value of the knoop hardness at the time ofnot adding the additive

The obtained results are collectively shown in Table 3 described below.

Furthermore, the evaluation of the knoop hardness was shown as the filmhardness in Table 3 described below.

TABLE 3 Degree of Acetyl Durabil- Substi- Additive Film Aging ity oftution of Com- Thick- Film Color- Polar- Film Cellulose pound Added nessHard- ation izing No. Acylate Number Amount (μm) ness (Light) Haze PlateNotes 301 2.42 1-4 10 61 A B A A Present Invention 302 2.42 1-6 10 57 AA A A Present Invention 303 2.42 2-2 10 58 A A A A Present Invention 3042.93 1-4 10 58 A B A A Present Invention 305 2.93 1-6 10 62 A A A APresent Invention 306 2.93 2-2 10 60 A A A A Present Invention 307 2.871-6 10 41 A A A A Present Invention 308 2.87 1-6 10 26 A A A B PresentInvention 309 2.87 2-2 10 24 A A A A Present Invention

Here, the added amount of the additive is denoted by parts by mass withrespect 100 parts by mass of the cellulose acylate.

As it is obvious from Table 3 described above, it was found that all ofthe compounds denoted by General Formula (A) in the present inventionwere able to express preferred film hardness without depending on thedegree of substitution of the cellulose acylate and thinning. Inaddition, the durability of the polarizing plate was also excellent.

In addition, it was found that the optical film of the present inventioncontaining the compound denoted by General Formula (A) had excellentdurability of the polarizing plate, excellent haze suppressionproperties, and small aging coloration due to light in the optical film.

Example 4

As described below, tyre durability of the polarizing plate wasevaluated.

(Preparation of Cellulose Acylate)

Cellulose acylate having a total degree of acetyl substitution (B) of2.87 was prepared. The cellulose acylate was added to a sulfuric acid(7.8 parts by mass with respect to 100 parts by mass of cellulose) as acatalyst, a carboxylic acid which was a raw material of an acylsubstituent group was added thereto, and the mixture was subjected to anacylation reaction at 40° C. In addition, the mixture matured at 40° C.after the acylation. Further, a low molecular weight component of thecellulose acylate was washed with acetone and was removed.

(Preparation of Dope for Surface Layer)

Preparation of Cellulose Acylate Solution

The following compositions were put into a mixing tank, each componentwas dissolved by being stirred, and thus a cellulose acylate solutionwas prepared.

Composition of Cellulose Acytate Solution Cellulose Acetate Having TotalDegree of Acetyl 100.0 parts by mass Substitution (B) of 2.87 and Degreeof Polymerization of 370 Monopet (Registered Trademark) SB(Plasticizer), 9.0 parts by mass manufactured by DKS Co., Ltd. SAIB-100(Plasticizer), manufactured by Eastman 3.0 parts by mass ChemicalCompany Methylene Chloride (First Solvent) 353.9 parts by mass Methanol(Second Solvent) 89.6 parts by mass n-Butanol (Third Solvent) 4.5 partsby mass

Furthermore, Monopet (Registered Trademark) SB manufactured by DKS Co.,Ltd. is benzoic acid ester of sucrose, and SAIB-100 manufactured byEastman Chemical Company is an acetic acid and isobutyrate of sucrose.

Preparation of Matting Agent Solution

The following compositions were put into a dispersing machine, eachcomponent was dissolved by being stirred, and thus a matting agentsolution was prepared.

Composition of Matting Agent Solution Silica Particles Having AverageParticle Size of 2.0 parts by mass 20 nm (AEROSIL R972, manufactured byNippon Aerosil Co., Ltd.) Methylene Chloride (First Solvent) 69.3 partsby mass Methanol (Second Solvent) 17.5 parts by mass n-Butanol (ThirdSolvent) 0.9 parts by mass Cellulose Acylate Solution Described above0.9 parts by mass

Preparation of Ultraviolet Absorbent Solution

The following compositions were put into a mixing tank, each componentwas dissolved by being stirred while being heated, and thus anultraviolet absorbent solution was prepared.

Composition of Ultraviolet Absorbent Solution Ultraviolet Absorbent(UV-1) Described below 20.0 parts by mass Methylene Chloride (FirstSolvent) 61.0 parts by mass Methanol (Second Solvent) 15.4 parts by massn-Butanol (Third Solvent) 0.8 parts by mass Cellulose Acylate SolutionDescribed above 12.8 parts by mass

1.3 parts by mass of the matting agent solution and 3.4 parts by mass ofthe ultraviolet absorbent solution were respectively filtered and thenwere mixed by using an inline mixer, 95.3 parts by mass of the celluloseacylase solution was further added thereto and was mixed by using theinline mixer, and thus a solution for a surface layer was prepared.

(Preparation of Dope for Base Layer)

Preparation of Cellulose Acylate Solution

The following compositions were put into a mixing tank, each componentwas dissolved by being stirred, and thus a dope for a base layer wasprepared.

Composition of Cellulose Acylate Solution Cellulose Acetate Having TotalDegree of Acetyl 100.0 parts by mass Substitution (B) of 2.87 and Degreeof Polymerization of 370 Monopet (Registered Trademark) SB(Plasticizer), 9.0 parts by mass manufactured by DKS Co., Ltd. SAIB-100(Plasticizer), manufactured by Eastman 3.0 parts by mass ChemicalCompany Exemplary Compound (1-2) 4.0 parts by mass Ultraviolet Absorbent(UV-1) 2.0 parts by mass Methylene Chloride (First Solvent) 297.7 partsby mass Methanol (Second Solvent) 75.4 parts by mass n-Butanol (ThirdSolvent) 3.8 parts by mass

(Casting)

The dope for a base layer prepared as described above and the dope for asurface layer on both sides thereof were concurrently and homogeneouslycasted onto a stainless steel casting support body (the temperature ofthe support body of −9° C.) in three layers from a casting port by usinga drum casting device. The peeling off was performed in a state wherethe amount of residual solvent in the dope for each of the layers wasapproximately 70 mass %, and both ends of the film in a width directionwere fixed by using a pin tenter and were dried while being stretched ata stretching ratio of 1.28 times (28%) in the width direction in a statewhere the amount of residual solvent was 3 mass % to 5 mass %. Afterthat, the drying was further performed by transporting the casted dopebetween rolls of a heat treatment device, and thus an optical film No.401 of the present invention was prepared. The thickness of the obtainedoptical film No. 401 was 6 μm, and the width thereof was 1480 mm.

In the optical film No. 401 described above, optical films Nos. 402 to420 of the present invention and optical films Nos. 421 to 423 of thecomparative examples were respectively prepared by the same method asthat of the optical film No. 401 except that the type of the additiveand the added amount were changed as shown in Table 4 described belowinstead of the exemplary compound (1-2).

Further, in the optical film No. 401 described above, an optical filmNo. 501 of the present invention was prepared by the same method as thatof the optical film No. 401 except that the following polycondensedpolymer (A) which was a polycondensed ester-based plasticizer was addedin the amount of 12 parts by mass instead of Monopet (RegisteredTrademark) SB and SAIB-100. In the optical film No. 501, optical filmsNos. 502 to 504 were respectively prepared by the same method as that ofthe optical film No. 501 except that the type of the additive waschanged as shown in Table 4 described below instead of the exemplarycompound (1-2).

Polycondensed Polymer (A): A polyester formed of an adipic acid andethane diol (a terminal is a hydroxy group) (Number Average MolecularWeight=1000)

Similarly, in the optical film No. 401 described above, the casting andthe drying were performed such that the film thickness of the obtainedoptical film was 25 μm and the width thereof was 1480 mm, and thus anoptical film No. 601 of the present invention was prepared. In theoptical film No. 601, optical films Nos. 602 to 604 were respectivelyprepared by the same method as that of the optical film No. 601 exceptthat the type of the additive was changed as shown in Table 4 describedbelow instead of the exemplary compound (1-2).

In the optical film No. 501 described above, optical films Nos. 701 to707 of the present invention were respectively prepared by the samemethod as that of the optical film No. 501 except that the type of theadditive and the added amount were changed as shown in Table 4 describedbelow instead of the exemplary compound (1-2).

[Haze Evaluation and Evaluation of Durability of Film Coloration Due toLight (Aging Coloration)]

The haze and the durability of the film coloration due to light wereevaluated by the same evaluation method and the same evaluation criteriaas those of Example 1.

[Evaluation Method of Volatility]

The compound denoted by General Formula (A) in the present invention washeated from room temperature to 140° C. by using a TG/DTA measurementdevice (TG/DTA7200 manufactured by Hitachi High-Tech ScienceCorporation), a change rate of the mass of the additive at the time ofbeing held at 140° C. for 1 hour (a change rate with respect to the massbefore being heated) was measured, and the volatility was evaluated onthe basis of the following criteria.

Furthermore, in Table 4 described below, Evaluation A and Evaluation Bwere denoted as “Absent”, and Evaluation C was denoted as “Present”.

A: The change rate of the mass of less than 0.1%

B: The change rate of the mass of greater than or equal to 0.1% and lessthan 0.2%

C: The change rate of the mass of greater than or equal to 0.2%

A polarizing plate corresponding to each of the films Nos. 401 to 423,501 to 504, 601 to 604, and 701 to 707 was prepared by using each of theoptical films prepared as described above, and durability of thepolarizing plate was evaluated.

<Preparation of Polarizing Plate>

(Saponification Treatment of Polarizing Plate Protective Film)

Each of the polarizing plate protective films formed of the opticalfilms Nos. 401 to 423, 501 to 504, 601 to 604, and 701 to 707 preparedas described above was dipped in 2.3 mol/L of an aqueous solution ofsodium hydroxide at 55° C. for 3 minutes. The polarizing plateprotective film was washed in a water washing bath at room temperature,and was neutralized at 30° C. by using 0.05 mol/L of a sulfuric acid.The polarizing plate protective film was washed again in the waterwashing bath at room temperature and was further dried with hot air at100° C., and thus each of the polarizing plate protective films whichwas subjected to a saponification treatment was prepared.

(Preparation of Polarizing Plate)

A polarizing plate corresponding to each of the optical films Nos. 401to 423, 501 to 504, 601 to 604, and 701 to 707 was prepared by the samemethod as that in Example 2 except that each of the polarizing plateprotective films described above which was subjected to thesaponification treatment was used.

[Evaluation of Durability of Polarizing Plate]

A durability test was performed with respect to each of the polarizingplates prepared as described above by the same method as that in Example2.

Here, the polarizing plates corresponding to the films Nos. 401 to 423,501 to 504, and 701 to 707 were evaluated by using the same agingconditions and the same evaluation criteria as those of Example 2.

The polarizing plates corresponding to the films Nos. 601 to 604 wereevaluated by using the following aging conditions and the followingevaluation criteria.

—Aging Conditions—

Aging Performed for 1000 Hours under Environment of Temperature of 60°C. and Relative Humidity of 95%

A: The change rate in the orthogonal transmittance before and afteraging of less than 0.4%

B: The change rate in the orthogonal transmittance before and afteraging of greater than or equal to 0.4% and less than 0.6%

C: The change rate in the orthogonal transmittance before and afteraging of greater than or equal to 0.6% less than 0.8%

D: The change rate in the orthogonal transmittance before and afteraging of greater than or equal to 0.8%

The obtained results are collectively shown in Table 4 described below.

TABLE 4 Durabil- Additive ity of Aging Com- Polar- Color- Film poundAdded izing ation Vola- No. Number Amount Plate (Light) Haze tilityNotes 401 1-2 4 A A A Absent Present Invention 402 1-4 4 A B A AbsentPresent Invention 403 1-5 4 B A A Absent Present invention 404 1-6 4 A AA Absent Present invention 405 1-7 4 A A A Absent Present Invention 406 1-11 4 A A A Absent Present Invention 407  1-13 4 A A A Absent PresentInvention 408  1-14 4 A A A Absent Present Invention 409  1-20 4 B A AAbsent Present Invention 410 2-1 4 A A A Absent Present Invention 4112-2 4 A A A Absent Present Invention 412 2-4 4 A A A Absent PresentInvention 413 2-5 4 A A A Absent Present Invention 414 2-6 4 A A AAbsent Present Invention 415 2-7 4 A A A Absent Present Invention 4162-9 4 A B A Absent Present invention 417  2-10 4 C A A Absent PresentInvention 418  2-11 4 C C B Absent Present Invention 419  2-12 4 B B AAbsent Present Invention 420  2-13 4 A A A Absent Present Invention 421Comparative 4 A D A Present Comparative Example Compound 1 422Comparative 4 D A C Present Comparative Example Compound 2 423 None 0 DA A — Reference Example 501 1-2 4 A A A Absent Present Invention 502 2-14 A A A Absent Present Invention 503 Comparative 4 A D A PresentComparative Example Compound 1 504 None 0 D A A — Reference Example 6011-2 4 A A A Absent Present Invention 602 2-1 4 A A A Absent PresentInvention 603 Comparative 4 A D A Present Comparative Example Compound 1604 None 0 D A A — Reference Example 701 4 A A A Absent PresentInvention 702 3-5 4 A A A Absent Present Invention 703  3-12 4 A A AAbsent Present Invention 704  3-13 4 A A A Absent Present Invention 7051-1/1-2/3-9 1/1/2 A B A Absent Present Invention 706 1-5/3-10/3-11 1/2/1A B A Absent Present Invention 707 2-7/3-1/3-14 1/1/2 A A A AbsentPresent Invention

Here, the added amount of the additive is denoted by parts by mass withrespect 100 parts by mass of the cellulose acylate.

From the results of Table 4 described above, it was found that all ofthe polarizing plate protective films which were the optical film of thepresent invention containing the compound denoted by General Formula (A)in the present invention had excellent durability of the polarizingplate in aging compared to the films Nos. 423, 504, and 604 which wereprepared without adding an additive thereto, and effectively suppresseddeterioration of the polarizer. Further, the aging coloration due tolight was decreased.

In contrast, in the polarizing plate protective film which was theoptical film containing the comparative compound 1 or 2 described above,an effect of enhancing the durability of the polarizing plate or ofsuppressing the aging coloration due to light was not obtained.

Further, it is assumed that the comparative compound 1 or 2 has highvolatility and has problems from a viewpoint of step contamination atthe time of manufacturing. Among them, the comparative compound 2 hadlow compatibility with respect to the cellulose acylate, and the hazevalue of the film was increased. In contrast, all of the compoundsdenoted by General Formula (A) in the present invention had highcompatibility with respect to the cellulose acylate, and thus had lowvolatility and a low haze value of the optical film, and therefore theproperties were excellent.

In all of the polarizing plate protective films which were the opticalfilm of the comparative example containing neither the compound denotedby General Formula (A) in the present invention nor the comparativecompound, the durability of the polarizing plate deteriorated comparedto the polarizing plate protective film which was the optical film ofthe present invention.

As a result thereof, it is possible to prepare a liquid crystal displaydevice having excellent performance as described above by using thepolarizing plate of the present invention.

The present invention is described with reference to the embodiments,but the present invention is not limited thereto unless otherwisespecifically stated, and is able to be widely interpreted within thescope and the gist of claims.

Priority is claimed on JP2013-144547, filed on Jul. 10, 2013, thecontent of which is incorporated herein as a part by reference.

EXPLANATION OF REFERENCES

21A, 21B: polarizing plate

22: color filter substrate

23: liquid crystal layer (liquid crystal cell)

24: array substrate

25: light guide plate

26: light source

31 a, 31 a′, 31 b: optical film (polarizing plate protective film)

311 a: cellulose acylate film

311 b: hard coat layer

32: polarizer

R: polarization direction

What is claimed is:
 1. A polarizing plate, comprising: a polarizer; andan optical film on at least one surface of the polarizer, the opticalfilm containing cellulose acylate and at least one type of a compounddenoted by General Formula (A) described below,

in General Formula (A), L represents an n-valent connecting group, nrepresents an integer of greater than or equal to 2, and A represents aheterocyclic group denoted by General Formula (I) described above, andin General Formula (I), R¹, R³, and R⁵ each independently represent ahydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, anaryl group, or a heteroaryl group, and any one of R¹, R³, and R⁵ isbonded to the L , wherein the optical film is formed of at least onelayer containing the cellulose acylate and the at least one type of thecompound denoted by General Formula (A), the at least one layer having aknoop hardness of greater than or equal to 215 N/mm², a haze of lessthan 0.3%, and an aging coloration in which an absolute value of achange in the value of the hue b* is less than or equal to 0.10 afterlight irradiation of 120 hours in conditions of irradiance of 150 W/m²,a black panel temperature of 63° C., and a relative humidity of 50%. 2.A liquid crystal display device, at least comprising: the polarizingplate according to claim 1; and a liquid crystal cell.
 3. The polarizingplate according to claim 1, wherein L is a single bond, an alkylenegroup, a cycloalkylene group, an alkenylene group, an alkynylene group,an arylene group, a heteroarylene group, —O—, —S—, —NR—(R represents asingle bond, a hydrogen atom, an alkyl group, a cycloalkyl group, anaryl group, or an acyl group), —C(═O)—, —SO—, —SO₂—, an arenetriylgroup, a heteroarenetriyl group, or a connecting group formed bycombining thereof.
 4. The polarizing plate according to claim 1, whereinthe total number of ring structures in L, R¹, R³, and R⁵ is 1 to
 6. 5.The polarizing plate according to claim 1, wherein n is
 2. 6. Thepolarizing plate according to claim 1, wherein the compound denoted byGeneral Formula (A) is denoted by General Formula (A-1) or (A-2)described below,

in General Formulas (A-1) and (A-2), R¹¹, R¹²,R³¹, R³², R⁵¹, and R⁵²each independently represent a hydrogen atom, an alkyl group, acycloalkyl group, an alkenyl group, an aryl group, or a heteroarylgroup, and X represents a single bond or a bivalent connecting group. 7.The polarizing plate according to claim 6, wherein X has a methylenegroup, and a carbon atom in the methylene group is bonded to abarbituric acid skeleton.
 8. The polarizing plate according to claim 1,wherein in the compound denoted by General Formula (A) described above,the number of >NH partial structures in molecule is less than or equalto
 3. 9. The polarizing plate according to claim 1, wherein a totaldegree of acyl substitution A of the cellulose acylate satisfies thefollowing expression:1.5≤A≤3.0.
 10. The polarizing plate according to claim 1, wherein anacyl group of the cellulose acylate is an acetyl group, and a totaldegree of acetyl substitution B satisfies the following expression:2.0≤B≤3.0.
 11. The polarizing plate according to claim 10, wherein thetotal degree of acetyl substitution B is greater than or equal to 2.5and less than 2.97.
 12. The polarizing plate according to claim 1,wherein the optical film contains at least one type of a plasticizer.13. The polarizing plate according to claim 1, wherein the optical filmis formed of at least two layers including the layer containing thecellulose acylate and the at least one type of the compound denoted byGeneral Formula (A) described above and a hard coat layer.